Help me please!

[TylerB]

I need someone who knows a bit about pregnancies to help me out here.
My ex-girlfriend and I broke up about 6 - 6 1/2 weeks ago. She called me last week and said she's pregnant. The sexual encounter in question would have been from around the first week of March. I am suspicious that she may be lying to me.

Here is what is making me suspicious;
After the one time we had unprotected sex, she was on the rag the following week.
It was over a month after that,, she said she took a pregnancy test that came up negative, but she said her doctor told her it was because it may be too early to tell, she says she took a 48 hour pregnancy test that came back positive. This is all hearsay, I haven't received any proof of this.
She told me she would be getting an abortion (we're both pro-choice), I told her if she needed anything, to ask, she said she didn't. This raised a flag because I make much more money then her, and she didn't ask for money for an abortion or even a ride to the clinic.
The other night, she called me, drunk, yelling at me about how much of a horrible person I was, and that maybe she should have the baby to teach me a lesson and went on to say she was going to kill herself, then wouldn't answer t phone for the rest of the night. Doesn't seem like something someone who was really pregnant would say? Really?

So what do you think? Is this something I should be worried about, or is it a cry for attention? I'm 22, she's 18, if that makes a decision clearer.