Hey Steph, so as I am not yet adult, I don’t really know a lot about the effects of substances on ADHD, but I was diagnosed with ADD (which is now just categorized as a form of ADHD) about 9 years ago. Here’s what I’ve learned in relation to your issue.
This may sound pretty obvious, but not all ADHD medications work for everyone. When I was first diagnosed with ADHD right around when I turned 7, I was prescribed Adderall and I took it every day for about three months. I don’t remember this, but according to my mom, it made me really depressed. They switched me over to Concerta, and I’ve been taking it daily ever since. I’m on 90 mg of Concerta every weekday now and it works great for me. Also, increases of your dosage will very likely increase its side effects on your behavior. Since Xaggatin XL already showed some negative effects, it’s not much of a surprise to see that the increase in dosage is having more negative effects. With me, I switched to 108 mg of Concerta for a week to see if it would help, but I just felt zombified and life was duller. Anyway, maybe try asking your psychiatrist about moving to another medication, because the Xaggatin XL doesn’t seem to be doing well for you. Performance wise, Xaggatin and Concerta are very similar. however, I haven’t found any information about differing effects on side effects of the two. I personally have never experienced an increase in agitation or irritation besides when I have been increasing or decreasing the amount of Concerta I’m taking for a couple of days. If I don’t take it at all for 2 days, I do experience that. That’s all I know and I hope some of it will be helpful. Here is a link to a pdf that has a comparison of the two medications. https://www.sps.nhs.uk/wp-content/uploads/2018/04/Methylphenidate-March-2018.pdf