Possibly pregnant on birth control?

I am currently on a combo pill for birth control. I used this pill prior to conceiving my 7 month old son without any issues. I was off the pill for 1 month when I became pregnant, so apparently I am pretty fertile. Knowing this, we have been careful even on the pill since he was born. I started a progesterone only pill in May due to breastfeeding, but I was unable to continue nursing, so I started the combo pill again in June when he was 3 months old. I have been on a regular schedule with my cycle since then just as I was previously on this pill.

My concern, though, is that it may not be working 100% right now due to a stomach bug I had a few days ago. I know vomiting/diarrhea can make the pill less effective, and we have had sex without a condom since then. I know the pill would keep me from ovulating, but if it’s not working correctly and I did ovulate, that would have been a couple of days ago. Then last night, I had some spotting which is really uncommon for me at this point in my cycle. The timing of all of that is just making me a little nervous. If the pill didn’t work correctly and the spotting was maybe implantation bleeding, how long would I need to wait to get an accurate test result?