I understand when you say it seems like an impossible situation. You have to feel so much pressure right now, and I'm sorry.
If you don't want to sign, then don't do it yet. I'm sure she'll be angry and frustrated, but is that the worst that can happen? NO! Take the time if you need it! You're worth it, whether she admits that now or not. Don't do this just so she won't be angry or frustrated. Your feelings matter, too. Don't forget that!