This is a legitimate concern and has been addressed to some degree in some areas. Unfortunately we don’t have a perfect way of knowing that a specific specimen is from a specific species. Two very similar skeletons could be from the same or closely related species. The same goes for development over the life history of a specific organism. Adult humans have a different skull to height ratio to babies, but the ratio between toddlers and young chimps is very similar.
Fortunately we have many different aged animals of the same species in the same context to compare. We can see the infant, child, adolescent, adult, and aged forms for many species and this acts similarly to transitional fossils, they help close the gap. We can be more sure with more hints like sharing a space, being buried in the same context, having the same nitrogen isotope ratios in teeth, and eating the same prey. Lots of other things can act as clues to the relationships and make us more or less certain of a given relationship.
That said, fossilisation is rare. Not all that many individuals will be fossilised. Different types of tissue fossilise to different degrees and in some cases not at all. If an animal is mostly spongy material they may degrade too fast to fossilise and preserve structure. Other examples may only leave their imprint as a hollow or pressing of one material into another. I think the record is very sparse and will remain so, but adding more example allows more connection and conclusions to be made.
First and foremost, you sound like you really need meds. The way the your medication was managed to when you were younge was likely due to it being too high a dose. It also may have been the wrong medication for you. If you tried ritalin and it didn’t work out very well for you I would recommend trying dex amphetamine, and vice versa. They work differently and have different side effects, and some people are very well suited to one while finding no function from the other.
The side effect you’re describing of a loss of appetite is usually attributable to the amphetamine effect of too much stimulant. Remember that amphetamines were prescribed as a weight loss drug early in their development, so that side effect is to be expected.
To manage food while on amphetamines you often have to have either deliberate planned structured meals or you have to have meals at the right time to be able to make up for the skipped meals. This might mean having a meal before you have your dose then having your dose, skipping food through the day, and then after the last of the dose wears off having another meal. I personally only eat once or twice a day, and always in the evening after my meds have run out. There is nothing wrong with doing that as long as you get sufficient food.
As for the job I would recommend thinking about what you actually do thrive doing. I sucked at working in an office but I work in disability care now and have wildly different clients with very different needs, so every day is a new and stimulating challenge. Doing the same thing, especially something like paperwork, every day with minimal variation would not work for me at all. Maybe you are trying to do jobs you aren’t suited to?