I have had a mucus at the back of my throat and have what's like a dot on my uvula I think I may have a std? As my girlfriend did give me oral and I kissed her after

Throat mucus is. very common, especially during allergy and URI seasons. It is not a sign of STD. Neither is a "dot" on your uvula. It sounds like you have general concerns about exposure to STDs, which is good to be thinking about at your age. I recommend that you review good quality STD materials from the CDC.gov or talk to an adolescent health specialist to address your sexual health concerns.