Hey Jake! That's a very tough question. I totally get your point though. I'm sure it kind of feels awkward to not have ordered anything while inside a bar. It might feel like people would think of you as a cheapskate or that you can't handle your alcohol but the truth is, nobody really cares that much.
As long as you don't act like a wallflower, I think you'll be good. There's no hard and fast rule for how long you can stay inside a club without ordering anything, but if you dont really wanna drink, dont for yourself.
Order some Sprite and tell everyone it's a Vodka-7.
Oh, and if you wanna go dancing, order something hard. Beer can make you sleepy while cocktails with a lot of sugar can give you a sugar high but a sugar crash as well.