That's not something I ever kept track of, but I would guess it's a low number. These are the ones that I can remember off the top of my head:
We know about Carol Marcus because they had a son together, but that was from the movie, not in an episode.
And there's Edith Keeler from "City on the Edge of Forever". They may have slept together, but I don't think that was confirmed. However it may have been implied.
In "The Paradise Syndrome" he got Miramanee pregnant, so that's confirmed.
I don't think he ever got that far with Rayna in "Requiem For Methuselah".
There was Deela in "Wink of an Eye". I think we see them after the fact, when he's putting his shoes on while sitting on the bed, so that would be implied.
I don't think he did anything with Elaan in "Elaan of Troyius".
KIRK: Elaan, two planets, an entire star system's stability depends on it. We have a duty to forget what happened.
ELAAN: Could you do that? Could you give me to another man?
KIRK: My orders and yours say that you belong to another man. What happened, what happened was an accident.
So that's the third time.
I'm not sure about Odona in "The Mark of Gideon", but I don't think anything was confirmed. Plus it would have been hard with all those faces staring at them.
So in the actual episodes, I would guess maybe three times it was implied.
The answer is 5 confirmed times. Besides the ones you mentioned. There's Drusilla in Breads and Circuses, after they embrace it cuts to a burning candle, then fades, then fades back to Kirk who's sleeping on the bed. Afterwards the Proconsul Claudius says:
CLAUDIUS: Because you are a man, I gave you some last hours as a man.
KIRK: I appreciate that.
KIRK: I appreciate that.
Pretty good guesses GBG and I'll call it your turn