Sounds like it could be too high a dose if you get jittery, been there at 30-40mg but 20mg + 10mg both extended release later in the day works really well for me.

Remember that the way Ritalin (methylphenidate) works is not by boosting dopamin but rather slow down dopamin uptake. You still need to create the first "spark of dopamin" yourself that then slowly snowballs itself stronger. I'd say you need to take it at least a few days to weeks to see an effect and learn how it affects you. Start at just 10 to 20mg. Otherwise try another variation of methylphenidate like concerta or medikinet.

Medication + therapy is the magic combo. Adderall was the magic bullet for me but I was lucky, and I hate that it only works for a limited time each day. And even then, it just makes actually doing things not suck. The drive, time management, and understanding what motivates me all come from therapy

The best analogy I found was it's like wading through a river to get to the other side. Medicine gets you out of the river, but you need therapy to find the bridge and cross it.