This girl I've been seeing for a few months, I *think* she may have just started seeing another guy.
I don't want to come across as desperate/too needy and texting her everyday, or constantly asking her out. But I also don't want to let another guy buildup with her.

How do I handle this?

I'll mention that this girl DOES think I'm a big player/ladies man, so she probably doesn't currently think I'm that desperate.

I had that many times, when I was dating a girl, and she mentioned she also goes out with other guys. NEVER show that this affects YOU!! In the end, I was the still one doing her

You don't ask about the other guys, or how their dates are. And if she asks you what you think, you answer: sure, that's ok / You player / slut!

Well she hasn't actually said anything to me. Just a conclusion I put together using random things she said and some facebook stalking ( ) so I haven't shown any jealousy or anything.

I haven't f-closed, but I like this girl and the biggest obstacle has just been that we've been going kinda slow (3 REAL dates, 3 months) and I feel we lost some momentum now.
I understand I could pull back to make her chase a little (I did freeze her out for a bit and it worked pretty good I guess), but I'm worried that it will give this guy a bigger chance.
Any ways I can subtly disqualify this motherfucker like a BF destroyer or something? Will pushing her to see other people help?

This other guy works with both of her roommates (which I haven't met and all 4 are friends) at a restaurant/bar so he has an edge there.

Hi maharishi mate

I don't think you have build enough attraction to play the PUA-trics. She already forgotten about you, but she is too nice to break things off.

Escalate!!!! DHV!!! And other guys have no chance at all

We went out last week. She asked me. We had to reschedule a number of times