@Essie, it can be worrying to find a mystery lump, but there’s a good chance it’s absolutely harmless! Check out my run through of common causes of lumps & bumps here! It covers both the normal stuff (skin tags, moles, pearly penile papules -yes, that’s a real thing!) that so often gets mistaken for an STI plus everything you need to know about genital warts – the number one STI around! Of course, if there’s any doubt, the only way to know for sure is to have it checked!
Good on you for thinking about these things and making choices for yourself! It can be awkward to bring up and hard to stand your ground, but I agree with @Aunt_Flo communication is key!