Are these outfits the appropriate attire for bars at midtown?!

Jennifer's birthday party is this Saturday. It's going to be at someone's apartment and there are plans to hit the bars at Midtown afterwards. My dominating thought was how out of place I would feel in this situation. I don't know any of her friends, nothing of what's going on with her life, and my sole anchor in that place probably knows more people than I do. Why should I go? The thing is, she needs a gal pal to this thing. And a part of me wants to feel at ease in these sort of get-togethers. At the risk of sounding ridiculous, I'm having a hard time figuring out how to dress for this. I feel lame admitting that but I didn't pick this up in college. I went to one bar and felt clumsy in my attire the whole time! Not to mention my feet were killing me in those heels.

I have clothes. I just don't know if any of them work for this. According to Steph, heels are the default for this kind of thing. She says nice flats could work too. Maybe I'm stressing too much about this but if only I had been out to more of these shindigs... I wouldn't be using the word shindigs. And it would be easy to say, 'oh yeah, I'll be there' and just magically know how to dress myself for this.

Anyway, I don't know if my ominous feelings will sway me towards not going to this thing. I want to go out at night but with a huge group of close-knit friends who are complete strangers to me? That is the question.