I am 28 years old with hypothyroid and hashimotos disease, i'm currently on synthroid (thyroxine) 225 mg, wondering if i should see a thyroid specialist?

Maybe: If your doctor is monitoring your thyroid and the values are in the normal range, he or she can take care of it. If ou feel uncomfortable with that you should see the specialist.

Probably: That's a fairly high dose. Hopefully you're taking brand name synthroid, (thyroxine) not a generic. Your doctor should be doing blood tests to make sure your levels are normal. Visiting a thyroid specialist wouldn't hurt, would be a good second opinion, and could be reassuring if you're concerned.