Late period, recently took antibiotics but had a bad reaction?

[Jane_16]

I'll try to be brief

I've been on the pill for almost a year now.

I recently had to take antibiotics for a stomach infection and my doctor told me to take my contraceptive pills at the same time to keep the routine. I understand all the consequences of them not working on antibiotics that's not the problem.

I've been on the week off from the pill for 4 days now and haven't got my period, I usually get it on the 4th day. Thing is with my last tablet I forgot to take it at night so I took it the following morning (within the 12 hour timeframe you're allowed if you miss one).

I haven't had sex in well over a month, not since before my last period just to say. I was too sick to even consider it then I had exams so my partner and I haven't had a chance, just to rule out pregnancy.

When I was on the antibiotics I was getting some very heavy breakthrough bleeding. Would my delayed period be caused by the antibiotics or just because I took the last pill a little late.