I don't tend to use the term "slept with", because I've had sex with guys without literally sleeping with them, and so have friends of mine, etc.
For me:
Slept with = had sex with
Sex = any form of physical, mutual sexual activity, whether it's oral, anal or vaginal. Masturbation with each other is my soft cap on this.
I know my definition of sex is fairly loose, and much more relaxed than a lot of other people's, but for me, if me and another guy are feeling each other up, there's nothing to stop us having anal sex. There's no reason I would do one but not the other. In a stricter definition, it could be just oral, anal and vaginal, but it definitely doesn't have to be just vaginal sex. If oral sex isn't sex, then lesbians can't have sex, and that seems a strange thing to say. If two girls are in bed with each other and are licking each other, playing with each other etc., in a way that a man and woman would do when they have "sex" - it seems stupid, to me, to say they aren't having sex.