Early period after HcG trigger... Anyone else?

Jessica
I did 11 days of Gonal F and triggered with Ovidrem on a Tuesday. I had spotting the 4 days later on Friday, then Saturday bright red period for the whole day. I didn't have anything Sunday until late Monday night, again bright red. Then nothing Tuesday morning and took a PG test just in case (negative), and I called the doctor anyway to ask because it was concerning. She told me that it may be breakthrough bleeding, since I've been doing fertility treatments for an extended time. She also said to me that if I experience bright red again, then it's my period and I must start my birth control pills. 
Did anyone else experience this with Gonal F and Ovidrel? Normally I start my period like a week and a couple days after I trigger if it's a failed cycle.