Need help please

So I was on birth control for about 1.5 years. I decided I was going to stop taking it. My sugar pills lined up with the week of Christmas and I got my period.

I haven’t had a period since. I am now 11 days late and still no sign of my period. I’ve experienced cramps (very slight and only here and there) that seem very similar to what I get during my period.

I have had both protected and unprotected sex. We aren’t necessarily trying, but not preventing it either.

Well. Our financial situation changed quite a bit and me and my husband decided I’m going to start taking the pill as now it’s not really in the books for having a kid due to what happened with our car.

At 7 days of my period being late I took a pregnancy test. It was negative. I took a second one today (11 days late) and it still says negative.

Now my question is, with both tests saying negative is it safe to say the no period is just a result of quitting the pill?

If that could be a reason, can I go back on the pill immediately or do I still need to wait for my period to come first? I looked at the pamphlet that comes with the one I’m on, but there’s no answers about a situation like this.