If she is old enough to go into heat then she is old enough to get pregnant so I would definitely keep her on a short leash until you have been able to get her spayed, hopefully in the very near future.
What is her name? How long have you had her?
When you have made enough posts people are going to want to see pictures...FYI
I am glad you are not planning on breeding her but be very careful it does not happen anyways. That would be very sad.