I am not a fan of methylphenidate, I will say this.

It is very hard to start a new drug like this with many side effects, using
limited dose forms.

I think you need to consider using immediate release form 3 times a day,
where you can tell what is going on better. Once you understand the different doses, you can then move on to long acting.

Concerta is a very long acting drug, with minimal choices, dose wise.
Most of the adults I dealt with on Concerta over time ended up with breakthru
doses of methylphenidate immediate release added on.

When you start methylphenidate there are different effects, than when you have been using it at one dose for a while. This is due to tolerance.
All treatments with methylphenidate involve some rebound. The higher the dose the more the rebound can be.

People with anxiety issues often cannot tolerate stimulants. It may be that way for you.

You can test the effects of the Diosmin by dropping it for a week or two and seeing if you get the same side effects without it. In general flavonoids like it are not a contraindication with methylphenidate, but there are no guarantees.

If your country of origin has Concerta, it also has methylphenidate in other forms (immediate release).