
I would'nt be so anxious about it one of my girls first season didnt come until she was 13m

you usually see a slight change in mood (not always) some become grumpy others very affectionate just think us girls and mood swings!
sometimes males in the park etc: will let you know as they tend to want to sniff thier rear end enthusiastically!
if you suspect then just pat with a tissue occasionally and you will soon know.
then keep her away from males I dont bother taking my bitches out a good run in our garden is good enough for them .
A season lasts for 21 days but be careful for another week to be safe
A good book "the book of the bitch" available at amazon is full of information and well worth having.
HTH
Roni