Nervous to meet up with a guy after some behavioral changes

I (16F )am meeting up with this guy(17M) I started talking to about 2 weeks ago on instagram. In the beginning he was really sweet and funny, and I’m not saying he stopped. It’s just a little different. We are planning on going to the mall on Sunday and he suggested doing something afterwards. That something was me sucking him off in his car. Which don’t get me wrong I’m fine with and I’m excited since it’s my first time. But over the days he’s went from calling me sweet names and complimenting me to just being really horny all the time. I’m not super worried about that but he switched to calling me a slut. Which I did say was hot so maybe that is my fault. But every time he asks to do some thing or not he even ask like saying “I’m gonna smack your ass” or “I’m gonna suck your tits” I usually just say like “yeah I’m fine with that” and instead of saying something like “are you sure? I don’t want to make you uncomfortable” like he did in the beginning, he’s switched to saying “yeah I know I can do that, you’re my slut” did i put this on myself by saying i like being called a slut? I just feel like he’s changed a bit and I don’t want him to cross any boundaries when we are in person. I’d really like some clarification from guys or maybe just some advice in general please!!