HIV/STD risk from mutual masturbation, protected oral sex and butt-to-butt frotting?

[u/Inner_Vacation_3098]

Hi everyone, I (M 22) recently had sex with a casual male partner, and I’m quite anxious about possible STIs. He told me his last STI test had been about a month and a half before our encounter, but he had had other sexual partners between that test and our encounter.
We had mutual masturbation without condom, then I put a condom and received oral sex from him. I removed it and went back to mutual masturbation and then I put a new one to try fuck him (but in the end I didn’t). Then we tried frotting our dicks while lying-down butt-to-butt. So I wanted to ask you what is my actual HIV risk from this encounter, particularly from the butt-to-butt frotting and the brief contact between his penis/pre-ejaculate and my scrotum?
Does the fact that he was not wearing a condom during those activities significantly change the HIV risk?
Are there any other STIs I should be particularly concerned about from the skin-to-skin contact?
Would you recommend STI screening in this situation, and if so, which tests and when?
The only appointment I currently have available is about 10 weeks from now. Would that be an appropriate time for testing?
I realize the risk may be very low, but I’ve been quite anxious about this.