When to take a pregnancy test? Google is confusing me

I had sex maybe 14 days ago, give or take. However I didn’t get my period this month. My period was supposed to come last week and I am super afraid I am pregnant since I didn’t get my period. I am on the pill but my boyfriend doesn’t pull out — I have also never not gotten my period on birth control. If I take a test tomorrow will it give me an accurate reading?

I always hear stories about how women get a negative and then a couple days later it’s positive and I just want to be like 100% sure that I am not. Also should I use a dollar tree test or would I be better using a First Response. I will pay whatever amount to get the most accurate reading