Hey Bro, Ill help you with this.
So oral is classed as a very low risk for transmission of STIs for various reasons. Most Drs do not feel that a single oral exposure warrants testing. Fingering (masturbation) is zero risk for STIs so we will leave that one there.
In your words "I am someone who always had discomfort around my bladder on and off."
STIs do not cause this symptom. It would cause burning on urination and discharge (usually pus type) or it could be asymptomatic (no symptoms).
Really the GP should not have given you antibiotics without testing (According to the UK BASHH guidelines, without proper symptoms this is not good practise) but its fine, its happened. There is a chance this could skew the test at the 22 day mark, bit given that it is 15 days after the abx it should not.
As a whole, the encounter was low risk and should not cause you concern. I can bet the reason the bladder pain is playing up is because of anxiety, but try to remember that guilt does not equal risk.
I have no STIs but have constant pain on my left testicle. If you are concerns see a GP or urologist but I can be fairly sure it is not related to an STI. If it were me, I would continue to have sex with my partner.
As a side note, I live in the UK and if you search SH24, alot of areas in the country are able to get a free postal STI kit for peace of mind. But I really do not think it is needed. Try to relax.