I don't go by what did your male think, are the girls mounting her. The girl on girl thing seems to be very early in cycle. Have not in 20 years done a smear. Thought those were usless. Make your money count. Do a progesterone test. You have been lucky. With what it all cost these days I don't understand not doing a Prog test. JMHO
My other girls were mounting her from day one, but she wouldn't stand for them at all either. Used to seeing flagging, standing for the girls, then introduce the male.
I had no reason to run progesterone since it was going to be a natural breeding with a bitch who has a history. The tests are $100 a pop here, so not something I do on a whim.