Heat

Hello! I love this website and I often refer to it to stay informed. Keep up the good work! By the way, this is not my first time to post. Thanks in advance for your advice.

My JRT's name is Jane and she's a fantastic little dog. We get lots of exercise and she is a very social little dog. She's almost 1 year and 8 months old and I'm concerned about her heat cycle. She had her first heat cycle at 10 months but hasn't gone into heat since then, as far as I know. She's a very "clean" dog and I wonder if I missed it somehow?? I was waiting to have her spayed and the vet told me two months after her heat cycle has finished but it seems as though she hasn't even started her 2nd heat cycle.... (!) Has this ever happened before? The first heat cycle was very obvious but not this time.... I'm confused...