Boyfriend going to Vegas/21st birthday

Okay y’all I need opinions. My boyfriend is turning 21 in September and wants to go to Vegas. I am 19 and will be 20 in December. He wants me to go with him to Vegas but I feel like I would hold everyone back essentially and be a party pooper since I’m not 21 and can’t drink or do any of the festivities you would want to go in Vegas on your 21st birthday. So I am choosing not to go, simply because I’m not old enough to partake in the birthday activities. What do y’all think I should do? I want to go I think it would be fun but I know he will want to drink and stuff and I’m not 21. Also the casino. Not sure but I think most you have to be 21 to go into, and I’m only 19.