is she pregant

7 months ago i tried to have sex with a girl one time only and after i cuouldnt get my penis aroused, i took off the condom and inserted my penis into her vagina for 20seconds. i did not ejaculate inside of her nor outsid of her. I was scared afterwards as it had been my first time. I gave her plan B 28hrs after. It has been 7 months and she has not gained any weight and nor has a belly. she has mentioned that she is gaining weight and she told me shes 2 months pregnat and claims its someone else she was with>?
do you think i might be the cause of her pregnacy...i mean is she lying to me?

[jaygon]

I would not even stress about it if she say's its not yours then leave it at that move on,