a "thing"

so me and this guy have been hooking up for a while..I'm only 16 and he's 17 and he has had sex before a couple times and ive only kissed people...we decided that we want a "thing" which is like being exclusive but not really dating (for people who don't know) but he wants to move very quickly and idk if I'm ready..it seems like that's the only thing he wants...so if anyone has advice id really appreciate it.