Is My Corn Snake Gravid or Not?? :s

[lexfish]

Hi,

I've had my corn snake together with a male, (both got them checked and they're both def a male and female) for a month and he kept trying to mate with her; lying next to her, nipping her, writhing on top of her - but it seemed like all she wanted to do was escape! She wouldn't lift her tail up for him, so I'm not sure if they've actually mated or not - I never actually saw them locked together... Is there anyway to tell if she's gravid, cause I can't feel any tell tale bumps and she's still eating and everything.

And if she's not pregnant, why would she not mate with the male? She's 2 and a half years old (supposedly) and big for her age, over the weight limit etc.

Any advice would be greatly appreciated, this is the first time I'm trying this! :s