Home pregnancy test worth it?

well im not 100% sure if im late for me period... i had a baby 4 months ago and had one period at the start of july, started bcp for the first time on the same day, had two smaller periods throughout july (not sure if they were breakthrough bleeding or actual periods) and im not sure when my last breakthrough bleeding started. im wondering if i should bother going to get a test tonight (its 10pm) or if it wont even come up positive because its not my first urine of the day. my test with my son was after i was a week late and was in the middle of the day but if i were pregnant i could be anywhere from 4-5 weeks. i was 5 1/2 weeks with my son when i got symptoms, the two days before i tested. since im nothing but tired (but a 4 month old could contribute to that) i dont know if it would be a waste of time. what do you think? should i bother tonight or just wait til the morning or a few days because im not even sure if im late yet (easier to test with first pee)?