I have adhd. The posts above are too long for me to read but can share experiences.
I've tried mirtazapine, sertraline, citalopram and escitalopram.
Mirtazapine - I couldn't do it - I was so hungry and because of the ADHD I couldn't control it. However I slept beautifully for the week I took it. But no.
Sertraline- it killed my focus and motivation. It did work when I took it consistently every single day at the same time and exercised and ate well. Was a nightmare to taper off - lots of IBS symptoms.
Citalopram / escitalopram - by far the best and least symptomatic for me. Not hard to come off. Difficult to taper up but I've gone very slowly e.g. 5mg a week, only increase at weekend. Escitalopram is cleaner.
Op, you mentioned insomnia, did you actually try anything to help with that? For example my adhd coach suggested magnesium glycinate 20 mins before bed - really helps. Also - promethazine is a drowsy antihistamine and is OK for bad insomnia once or twice a month. Insomnia in summer - with adhd we don't produce enough melatonin in summer - so melatonin (off label from america) could be an option, getting daylight first thing (natural or via a SAD lamp) can help with evening melatonin production, good sleep hygiene, an Epsom salt bath soak (excellent for anxiety, as is magnesium), dim the lights at night and pull curtains in evening helps. You can also do sleep specific CBT
There's a good book called Why We Sleep which I also recommend.
Vortioxetine - my adhd psychiatrist recommended this one as meant to help with focus and motivation
I tend to take anti depressants for 6 months to get myself back on track then stop for 18 months, been in this cycle for about 5 years now.
I find CBT can also help with goals - but if you pick only one goal at a time (for example wanting to improve sleep, or wanting to exercise more).
Tracking impact of hormones helps a lot too.
Diet wise - there is some evidence for improvement of adhd with a mediterranean diet - protein and healthy fats. Some favorite adhd friendly meals that pack so much nutrients for me are baked mackerel mixed with avocado and penne pasta and olive oil. Or seabass, new potatoes and greens, so much nutrients. Making up a big roast chicken at the weekend in one pot.
If I'm honest I probably use food more than anything (alongside adhd meds) to regulate and focus - always same rough timings for breakfast, lunch and dinner (in the Why We Sleep book it explains that this helps sleep, for example it's one reason why blind people don't all have insomnia).
Re. Adhd diagnosis, is 3 years via Right to Choose pathway?
Edited to add --sometimes you have to think of it as what are the least worst side effects I can live with. As everything has them. I can't stand gastro issues for example but dry mouth I can live with - sucking sweets, keeping up electrolyte balance can help.