What's also a bit weird - and you asking about my first public scene just made me think of it - my first proper sex scene (as in one where you actually saw anything going on rather than fade to black) was with the woman I was dating at the time. So that does throw things off, that was different enough that there was some focus on that rather than the general weirdness of sex scenes.

And - same film - we had a drunk orgy scene, and the champagne was real to get everyone loosened up first. So we weren't going into it cold which again, changes things.