Taking turns with my gf doing anal sex

My gf has been talking about anal sex for a while now, and I finally convinced her to try it. It was her first time, but she was really into it. We had a good time together, and I was impressed with her skills. After she sucked my cock I returned the favor and licked her pussy, having sex in different positions. 
Before I fucked her in the ass, she told me she wanted to fuck my ass with a strap-on. I was curious, so I went along with it, having a good time. It was fascinating, and after that, I fucked her tight ass, filling it with semen.