Possiblity of Pregnancy *Please Help*

Okay so a little background. I am 19. And I pride myself in knowing as much as I can to be safe in my activities with my boyfriend, but somethings are beyond my knowing so any help would be great.

I have been on and off birth control for a couple years, pills always make me really sick so I use the bc patch called Evra. I was on it for about 7 months straight then stopped for a couple months. I started again about 3.5 weeks ago(2 weeks in I started feeling the effects the patch gives me). I know it takes at least one full cycle to get the proper protection from it, but along with the patch I always make my boyfriend wear a condom. I’ve never had issues before but yesterday it broke and he ejaculated inside. Another factor is it was the day I took off my patch so I could have my period. (it usually takes from the day I take it off, sometimes one day or 3 to start my period, so it’s uncertain if anything has happened, I’m just really freaking out).
I’ve got a pretty good sexual education background, and have been doing research. I don’t need to be told that at any time there is a chance of pregnacy but I need people to reaffirm what my research came up with.

My chance of being pregnant is lower at this point, rather than a couple weeks before my period, correct?

And I know if my period doesn’t come I should take a hpt. How long do I wait, what’s the earliest I can get one of those and trust it’s results before having to take it to my doctor?