I've never had one take longer than 9 months for their first, but my Maya has her heat cycle every 5 months which is a little faster than most Beagles. If I was not obsessed with watching for the signs I would probably never know when my girls were in heat. Of course I have boys also and they help to keep them clean, but rarely do I EVER see a spot anywhere. I think it is very possible she has had a cycle and you were just not aware.