Bump in vagina??

A few months ago I found a bump inside my vagina on the top. I can see the bump with a mirror and feel it too. 

I had the same partner for a while now and we always use a condom, and I'm on birth control, but could this possibly be an STD or is this possibly a cyst? Or, is this more of a cancer like thing. 

Im only 17, so I'm going to speak to my mom soon about seeing a gynecologist, but in all honesty I'm a bit scared to ask. Should I be worried about this bump or not?

Have you experienced any symptoms accompanied by this, such as pain, itching, or burning? If not, I think it's just a normal cyst that can go away without treatment. See a doctor if your bump becomes inflamed. That could be a sign of infection.