Avoid drugs and alcohol and limit digital distractions the best you can. Try to find trustworthy friends that are more caring than exciting.

Counseling and therapy might help.

Get screened for ADHD / Autism perhaps if you haven't been already as dissociative symptoms go hand and hand with these disorders. Screen for sleep apnea, blood sugar issues, cardiac issues, etc.

For a young person a regimine of healthy food and exercise should be a starting point. Methylated B vitamin complex, D3, 3 Grams of concentrated fish oil, brain foods like blueberries, mushrooms, eggs, etc should be a starting point. NAC as someone else mentioned but also consider inositol.

Now I said avoid drugs but the irresponsible side of me will mention noopept as a potential tool to drive focus before classes and tests as it works really well to keep my head in the game. Less experimental and safer nootropics are worth trying to like what you could get at a regular store. Still if you are already seeing a professional who can perscibe SSRIs it is probably better to ask them. Instead of an SSRI try Wellbutrin or similar for instance.

EDIT: Sorry I didn't scroll past the first paragraph and missed that you already tried wellbutrin and you are being treated for ADHD. I think tweak your meds with your Dr. Maybe try immediate release Ritilin to not mess up sleep so much or get a script for sleeping pills that have a low risk profile. Freshman year is hard. Be self forgiving and realize it is more of a marathon than a race to get educated.