She invited me to a party for our 2nd date - is this a no-no?

So I met this girl at her birthday party at her house in the country, her brother's friends and I were the live band (I the drummer). She wouldn't let go of my arm at the party and now we text everyday. I live in the city and she won't be moving here until July when she graduates high school, so we see each other about once a week. Our first date we went out to eat and walked in the park and then went to see her brother (he's also my friend). Now she is coming into the city for her friends birthday party tomorrow at a pizza place and she wants me to come. This will be the 3rd time I will see her, and it would be our second 'date'. Anyways, I don't feel comfortable going because 1) I don't really know her well enough to meet her closest friends 2) I won't know anyone there except for her 3) I would turn to alcohol to loosen me up but I can't get wasted. Should I tell her I have something to do and that we can meet up after? Or should I man up and go? I'm leaning towards the first option. NOTE: I also happen to work at a pizza place and I really don't like eating pizza anymore! (This party is at a pizza restaurant)

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