Is there a way I could get STDs?

Me and my girlfriend were both virgins and have had sex about 7 times and oral about 10. I fingered her sometimes. All the times I’ve had intercourse with her I used condom. One time without condom I stick the tip of my penis in her anus but for sure I know my penis didn’t go inside her but just the little entrance of the anus. Since she told me about learning about STDs I have been worried about that. I got a pimple in the skin of my penis but it’s the same color of my skin. I really don’t know?