4 days late BFN

This is my first post, AF was due 9/24, I'm hot, tired, heartburn won't go away, and (even though I have been vegetarian for 11 years) I ate McDonald's cheeseburgers yesterday! My husband went and got them for me because I was crying!

My question is, I had a mc 3 months ago, periods between then and now perfect 28 day cycles, but I'm still getting bfn's! Could I be pregnant? How long should I wait to do the next test?