12 year molars coming in at 18 acting like wisdom teeth/painful. Dentist wants to pull my two baby first molars and put me in braces.

May be needed. Obviously your growth and development is delayed quite a bit as far as your mouth goes. If your 12 year molars don't have the room to erupt properly then sacrificing baby teeth is probably the best option. Are you missing any other permanent teeth? Who is doing the braces, your dentist or an orthodontist? If it is your dentist then you may want to talk to an orthodontist for another opinion.
I agree. I would defer to the opinion of your dentist and agree that if your molars are impacting your teeth you should consider removal and braces.