I would test again. If it's still negative then still get blood work done to see why you're so late.
The morning after pill is not 100% effective, and loses it's effectiveness the longer you leave it after intercouse (ideally to be the most effective it can be it needs to be taken within 24hours).
The pill is also pretty bad for your cycles, and can mess up your periods so it's really no surprise your period late. Especially since you used the pill 2 months in a row...really it should not be used more than twice in a year.
I would say there is still a small chance of pregnancy, so the best way to tell is to wait until your doctor is back and get a blood test to tell for sure.
I've now skipped my 2nd period, which is really unusual for me. The m/a pill can make u skip 1 period, not 2. Talked to my Dr & I have a blood test referral to test for a few things including pregnancy. Gonna go do that tomorrow ( been procrastinating) but starting to get worried. The thing that pretty much confirms to me that I'm not preg is that I have had no morning sickness at all. I've had 2 children, but also 4 unsuccessful pregnancies on top off that & each time I've been so nauseous from day dot, granted I haven't been pregnant for 4&1/2 yrs. Weird weird. I did have an apt with family planning to get an iud put in, but after explaining all this to them, they want to know what's going on with my periods first which is relieving that I'll have Someone professional to investigate. I've never skipped one, let alone 2 periods in my life. Even bled thru some during my kids' pregnancies.