Letrozole Ovulation..

This is my 4th round of letrozole. I had my period 10/19 to 10/24 and took 7.5mg of letrozole 10/21 to 10/25.. I also BD on the 26th. I am CD 11, so I took an ovulation test that was negative this morning, but Im having sharp pains where my ovaries are.

How early can you ovulate on letrozole? Is there anything that would make me ovulate early? My peojected day of O is November 4th... usually dont get ovulation pains this early. I don't temp, just rely on my body and OPKs. Since I am having O pains already, should I test multiple times in a day to try and catch it?