I've been there and I've seen other newbies there... We get concerned when girls think we are gay. We think that's a bad thing because a gay guy doesn't bang girls. Truth is, being considered gay is not a big deal at all but it's something you don't probably want to be forever.
First off, I've pretended to be gay for an entire set. It started when a girl disqualified me almost immediately, so I came back with a stronger disqualifier (saying I was gay). Then, I acted insanely flamboyant the whole set (the chick kept screaming "Oh my gaud! He's soo gay!!"), and I banged the girl in the end (after giving her LMR). Not only that, but she STILL thought I was gay when I was dropping her off at her place the next day, even after I came twice while banging her.
So long story short, being considered gay will NOT hurt your game as long as you play the rest of the game correctly. Here's why she thinks you're gay:
1) You're wearing extremely tight clothes (common for PUAs)
2) You are very eccentric and bouncy (common for newbies. You'll learn to cool your jets and slow things down with time)
3) You are very feminine with your mannerisms (hit the gym and do lots of squats to hold your weight and shoulders like a man)
4) You are not escalating (Start escalating and she'll never ask if you're gay again)
5) You have a high pitched voice (combo of nerves and not speaking from the diaphragm)
6) You and you wing are acting like a couple (common for new PUAs who have separation anxiety from their wing because talking to chicks is scary)
7) You talk to more guys than girls (Common for any guys with approach anxiety)

You know more about style, fashion, designers, music, and pop culture than most guys and close to nothing about sports, cars, and other manly stuff (common for PUAs)
So we know why she thinks you are gay, and that being gay doesn't really hurt the set... What do you do about it?
1) Ask yourself, "How much did I escalate in this set?" If the answer is "not much," it's time to escalate. She is asking if you are gay because she likes you and is confused why you are not making a move. Kiss her.
2) Think about all the mannerisms from your set (did you dance flamboyantly? or do anything eccentric?)
3) Never react negatively to a statement by her. Just smile and laugh. If she says something you are wearing is gay, LEAVE IT ON!! It's more important than ever to stay congruent to your appearance and identity when you are being called out.
Anything left you need clarification on?