CD13 & 10mm follicle growth, advice please?

I'm on 1500mg Metformin and 150mg of Clomid, this is my 3rd and last cycle of Clomid, I have PCOS. I'm on cd13 today, had an ultrasound this morning and one of my follicles is 10mm (previous ultrasounds showed 6mm growth only) is this normal? I feel that this one just isn't going to trigger and make me ovulate. My only hope after this is ovarian drilling and a round of ivf! Has anyone had similar growth and still ovulated and become pregnant? Feeling very doubtful after 3 rounds and 2 years of ttc!