Boyfriend turning 21 and going to Vegas...

Hi guys. I need some advice on something. So my boyfriends almost 2 years is turning 21 in February and I’m 19 and won’t be turning 20 till July. He has been planning on going for around a year now. Ever since we talked about it, he wants me to go and I’ve made plans to go but the thing is I’m underage so I won’t be able to do all the things he will want to do since he’s turning 21.

At one of his family parties the trip was brought up and some of his family members that are over 21 agreed on going until one of his snobby cousins kinda laughed at my face and said “aw you’re still not 21 guess you can’t go” and the rest of his family kinda chuckled at it.

So honestly at this point it seems like it’ll be such a problem if I go since I’m underage and can’t go into anything. I’ve talked to him about it and it seems like he still wants me to go, but after what his family did I just feel stupid going.

Any advice? If you are in a relationship with an age gap like this.