Late period

So my period is late - 5 weeks late to be exact. I’ve took a test and it’s negative (phew!).

The only thing I can think that’s caused this is about 8 weeks ago I started Propanalol and wondering if anyone else is on this and experienced the same thing?

I am on the pill (only form of contraception) and have been for 13 years, I haven’t missed any and I am very cautious about taking it at the same time every day. I have never missed a period, if anything I am more likely to have ‘extra’ periods as opposed to missing them so this is very strange for me.