When to expect a BFP?

Am

Today is what should be the first day of my period. I tested and there is a faint, but definite line (yay!), but not a BFP. My very first pregnancy was a chemical. My second pregnancy I tested on what would have been my 3rd missed period day and it was a BFP. Could this one also be a chemical or do I need to wait longer for the BFP? Any thoughts?