Dude. Remember that no-one at all has the authority or the right to pressure you into telling them anything about your sexual experiences. If you identify as a straight male, then the first time you felt that you had intimate contact with a girl was sex..
Medical opinion about virginity doesn't take into account sex between biologically female men, or transitioning men.. and it doesn't matter! Sexuality and gender is so diverse, there's no way anyone is authorised to give a situation to every kind of gender and say this is when that person lost their virginity! It's totally up to you to decide when you lost it, and it doesn't even have to have happened in one event either. Losing your virginity is a process that happened when you wanted it to.
Like previous users said, if losing your virginity only happens when you get penetrated by a penis then there's thousands of lesbians who are virgins.. and of course, they aren't.
What about gay men, as well. Medically, they might never had penetrative sex with a biologically female woman, so are they virgins as well? of course not.
Sex is so varied and wide and can involve so many different things, it's up to you.