Sucking Cock with my new Girlfriend

Courtney and I have been dating for about a month and we've been having sex for two weeks. No sleep overs yet. So far the sex has been great even though we are still discovering each others bodies.
Last night I was going to spend the night in the city at her place, our first sleep over.
We went out for a nice dinner and since it was a beautiful night, we walked back home to her unit. In the elevator we were making out and my cock was starting to come to life. Courtney made a joke telling me to slow down, she suggested we go up to her pool/spa that is on the roof of the building. Sounded good to me. And yes, I did want to cool down a little bit as I was super horny.
Inside her unit, Courtney went in to her bedroom to get changed. I had to tell her that all I had was a pair of speedos, was that OK?
She replied back that she was hoping that was all I'd be wearing.
It is summer here in Australia, I wear speedos as underwear all the time. It comes in handy a lot, dropping in to the pool on the way home from work, going for a quick swim at the beach, I've even been out mountain biking and had the chance to go for a dip in a natural pool and speedos are convenient. While I wear them, I'm not super confident wearing them in public and I'd never have the courage to wear them at a pool party or something like that. Rooftop spa at 10pm at night with a pretty girl, that sounded like a good idea though.
Courtney comes out of her bedroom wearing a tiny black Wicked Weasel bikini. It is too tiny for a pool party (like my speedos) but it isn't indecent. It has thong bottoms which seem to be in fashion these days and she looks fantastic!
I had been making up some drinks and was still fully dressed, which she was not impressed with. She ordered me to strip down, which took me all of four seconds to whip my shirt off and drop my shorts. We started making out again and it was incredibly sexy us both wearing next to nothing in her kitchen. When Courtney caught me getting hard again she broke off our embrace and looking down at the bulge at the front of my speedo, told me I can't be full mast, in case there are people up there.
Courtney gave me a towel to wrap around my waist, she did the same and with drinks in hand we headed up to the pool/spa.
This was the first time I had been up there and it was really nice. I've alredy mentioned that it was a beautiful night as well. There was one guy sitting in the spa, otherwise the place was empty.
Courtney and I jumped in the pool and hung out there for ten minutes or so and then she suggested we get in the spa.

The spa was pretty big and we said g'day to the guy who was sitting there. He was our age, early 30's and was enjoying an ankara travesti adult beverage as well. We started chatting to him, Courtney said she had seen him around the building and he told us that it was his last night there, he was moving up to Cairns. Three of us just chatted for a bit and Sam (that was his name) said he was going to get another drink and asked us if we'd like one? At first we delined but he said he had to drink it before moving out the next morning. We accepted Sam's offer of a G