On the one hand an FSH of 10 is not what anyone would wish to hear, as many of us here are high fsh'ers we know this only too well. Yet, on the other hand, if she is young, then the FSH doesn't matter quite as much as we may immediately feel obliged to think. Sure the number of eggs retrieved may be less overall if she doesn't stim as well as someone with low fsh, but the quality should still be good if she is young.
I'm not sure that your emotional gut feelings towards her are as important as the objective facts so I would certainly wait to see what the fsh test comes back at when re-tested. Also, if she has just done a cycle recently, what was the outcome of that one in terms of number of embryo's and quality. If it was good, then surely things can't change so much in just a couple of months? If it was not good, then you have something else to factor into your decision.
Having said that, if you truly believe that if you don't cycle with her then you won't cycle at all, then I would definitely give yourself that chance with her. Or you will always wonder 'what if?'
Sending you another hug Calm.