AF was due 5 days ago, took a test and BFN but not sure if the brand is the problem, suggestions??

So my cycle is normally 31-32 days, got positive OPK on CD 21. AF was due on Friday or saturday and its now wednesday.. I took a PT yesterday morning (clearblue digital but not the one with weeks indicator) and it said not pregnant. I looked up some reviews though and a lot of people said that those arent the best to test with if youre only a week or two pregnant. Was going to try to get first response tests instead. Been feeling nauseas, boobs are heavy and veiny but not hard like usual right before AF, cant sleep at night but exhausted during the day, constipation, loss of appetite.. Suggestions? Thoughts? This is my first time posting, its been driving my crazy though so i needed to reach out so someone.. Please and thank you!