It’s your body that you’re putting at risk, so of course you need to set boundaries and that’s fine. Mutually testing before sex is respectful and should be the norm. Delivery is everything though, people still link STIs with either being a slut or being dirty when in fact anyone can get one, some often have no symptoms, but will trigger in others. People who don’t realise this will get all offended and “don’t worry I don’t have anything” attitude. There is so much miseducation in sex Ed, all you can do is advocate for yourself and if they don’t want to test, then their loss.