Titration question - can I swap from methylphenidate to lisdexamfetamine and back again?

I am currently on 54mg XR methylphenidate (xaggitin) I feel like 36mg was not quite enough, however I'm feeling like 54mg is too rough around the edges.

I take my meds around the same time every morning (7ish) with a protein shake and some carbs. I drink water throughout the day. Both of these things have been a challenge in themselves - I'm sure you guys know this struggle!

I'm finding that around 2pm - 4pm ish I am feeling groggy, not sleepy groggy, more like numb, a bit jittery, feels almost dirty chemicaly if that makes sense. I have not had these symptoms until thelis dose during my titration.

I have tried going back down to 36mg XR and taking a 5mg IR in the afternoon to see if this works better for me but it's also not quite enough.

After quite extensive research (and I know everyone is different and reacts differently to methylphenidate and dex) it appears that elvanse is somewhat gentler with its harsh side effects whilst being better on mood and focus.

My question is, if I change to elvanse and it's not right for me, am I able to change back to methylphenidate? Also how does this work once titration is complete and (hopefully) shared care is in place? Am I stuck on whatever I finished titration on or am I able to change again?

Thanks all.