I don't have a vest, but I do have a thick jacket that can be used for armor. Is that acceptable or do I have to bring an actual vest? I don't have any handguns, so vests with pouches are useless for me and are costly, so thats why I am asking this.

Body armor for protection is not required. You could play in a tank top and some shorts if you wanted to. The only thing that is required is full face protection( if you are a minor). If you are above eighteen the just eye protection is required.

A vest is definitely not required, I go with just a short sleeve shirt, or a hoodie if needed. A hoodie usually keeps the bbs from breaking skin short sleeve obviously not, just depends wht you can tolerate.