I use 'making out' as a blanket term for 'sexual activity' all the time. If I say "and then they made out" to describe a scene, I mean anything from kisses to explicit sex.
Then I'm afraid that you are simply using the term wrongly. It's certainly not in common usage with that meaning, so there hasn't even been time for a definition drift (as can happen).
For years I assumed "plaid" was pronounced "played" rather than "plahd" because I'd never heard it spoken aloud (We use "tartan" in Scotland) and that's what it looked like it should sound like. It didn't make me right. :)
(Sorry, on re-reading these paragraphs it may come across as me snarking at you, that's certainly not the intent, I'm just not sure how else to say it. Though knowing the way these things work, I'll come up with the succinct, elegant and obvious answer about four microseconds after I hit "Post")