Is it normal to have a side chick that my girlfriend doesn't know about?

So how would you feel if you found out your girlfriend was doing the same thing with a male friend? Lies can destroy relationships even if they're not found out.

If you're not sticking your dick in her she's not a "side chick"

Sounds like the "side chick" is just a friend if you're not banging her.
Maybe take your GF out to meet her and see if they click. Maybe she'll act different, be more open about herself and have some damn fun with you!
Nobody is perfect. Have a talk with your GF. Hell, talk to your "side chick" if you hadn't about some of the issues you are having. That way she too can either help you or maybe come clean and tell you if she likes you more than just friends.

Never cheat. It never works out. You wouldn't want it happening to you so man up if you simply don't want to be with your GF. That's another thing. The side chick might not be doing anything because you have attachments.

To me it sounds like your girlfriend is way different from you and doesn't make you happy at all. The best solution is to leave her. What you're doing now (if your side chick is indeed one, namely, you have a romantic relationship) is not normal. Also your relationship with your gf is not normal and healthy. If you just hang out with a female friend that's normal and ok but your relationship is still bad. The first thing I'd do is to tell my gf that I want a change in our relationship. If that doesn't work at all, I'd just break it after trying (maybe a couple of months, depends on the results). And then be careful when selecting your gf next time and keep in mind the aspects you want and those you don't want.

Sounds like a friend, not a side chick. Yes, you can have female friends even if you have a girlfriend.

So....you have a friend?

There's nothing wrong with having female friends, as long as things don't escalate further than just hanging out. If your girlfriend trusts you (and isn't insanely jealous and possessive over you), she should be okay with you having female friends.

There's no problem with having a female friend, and hanging out with her. The issue lies with you; you feel it's wrong because you know you like this girl and enjoy her company WAAAAAY more than your actual girlfriend.

Be honest with yourself.

Tell your girlfriend. Unless she is controlling, possessive and insecure she shouldn't have an issue with you having a friend.

Morality aside, it's normal in that's it's extremely common.

This is why people say "Men are pigs"