I will reply more to you privately, but if you were diagnosed with NVLD prior to age ten, it is most likely you or a representative could have proved yourself as a child disabled by SSA standards as soon as that diagnosis was learned and detailed by a medical professional with supporting information from your parents that would have satisfied the criteria to be approved as a child.
However, whether the SSA would have awarded benefits to you even if a disability could have been proved would have been another story, as that would have been dependent on the financial situation of the parents. If they had an income(s) more than that would allow you to qualify for SSI, as SSI is a financial-based disability program for those individuals that the SSA considers disabled AND with financial need, based on total household income, they would not even have looked at an application much or approved your case if the household income exceeded the allowable financial limits.
The question if you should be upset at your parents for not wanting to follow up on the NVLD, further medically documenting your limitations and applying on your behalf for benefits, depends on if they either knew you were like!y disabled at that time, could have received benefits at the time, or could have received additional help that was not already awarded you. Perhaps they either knew you could not financially qualify based on the household income, or they because of any conditions themselves just never even knew about disability benefits being allowable to children under certain cases.
If you as a child would have qualified for SSI because of limited household income that satisfied eligibility and because of a disabling condition that meets their disability standards, you as a child would have been awarded benefits retroactive starting from the date of the application, with the parent or caregiver most nurturing or able being designated the Representative Payee to handle those matters for you and to use that money for your needs.
You need not have had a specific Autism diagnosis then to qualify for disability benefits, as our youngest son was at age four or so just seen as nonverbal then, had numerous delays and sensitivities yet still got SSI benefits based on that and other !imitations I detailed. The process for determining eligibility in children is different than for adults, and so keep that in mind. For adults there is a five step process they look at, and I will include the link later. Having an updated medical report prior to applying with firm diagnosis, preferable mentioning poor prognosis, but at minimum mentioning moderate to severe difficulties with regards to performing day to day activities and having marked, moderate or extreme functional !imitations, that would be helpful. There are functional reports that can be filled out too by you, and/or Third Party forms too. SSA often does not advertise this.
It's a catch-22 in ways, as in order for a medical professional to document all that, you or a support person must detail that to them, as otherwise the SSA will say there is no reliable evidence. But, if you detail that to them, a non-specialist doctor may think you are more able, wise, social, or taking advantage of the system if you focus just on negatives or if too much detailed for limitations. A specialist though may be more understanding and instinctively ask the right questions, or they know how difficult is for many Autistics in the core component ways. The fact I,my wife, and our two children were able to get benefits though during the first stage and not having to appeal was largely because I knew the system, how to be truthful but focus on limitations and functional difficulties, in the forms I filled out, and to detail important delays for the children. I knew how to satisfy the rules as I know ourselves extremely well, love research and being detailed,factual and comprehensive in submissions there, being accurate, but using my obsessive and proactive nature there to our advantage.
Unfortunately, the system is rigged against those who do not have the same self awareness, belief, motivation, knowledge and persistence to not be swayed by their delays,any false statements by them, etc. Many cannot handle that stress of the lengthy, unfair, and rigid processes and procedures and give up. And heck many with conditions are not in that state of mind or have that specific ability to do such themselves or do not have effective lawyers,support person's to document everything to support disability according to SSA standards. The SSA is banking on this, so they often twist facts to support denial.
So,whether you should be upset at your parents should be your choice, but I just know I rarely worry now about things I cannot control as it's useless energy. This does not mean I felt I had to deal with my parents as an adult, but just that I never would have the answers why they did not fight hard for my rights to document our very dysfunctional states at that time. They were in denial,likely,or wanting to hide their wrongs. The anger I had at them was mainly because of the abuses and neglect,and medical neglect,as I do not think they had an SSI program then. I learned from my parents what not to do, and that is why we got benefits for our children at ages of around three and four respectively. All their needs are met, and any extra each month ABLE savings programs exist.
I am assuming when you suggested or mentioned you were denied SSI but have a pending SSDI case perhaps you applied for SSI and SSDI at the same time and the SSA either just thought your assets exceeded $2000 in allowable resources, not counting car and a home and/or your work credits were too much for SSI. Being denied SSI does not mean you are not disabled and you could be approved by SSDI in this case. You can thus get SSDI as an adult if you if you satisfy the 5 criteria in the next post, benefits retroactive I think six months from the date of the disability onset, or apply for DAC benefits if your disability condition began before age twenty two and your parent(s) contributed enough to the system, upon their retirement or death. For complicated cases, yes a lawyer is needed. For all our cases,I handled everything myself with no difficulty.