pregnancy test & abortion pill

I had an extremely stressful (June) month. (Last period was in May 24-28) I'm late by a month. My assumption was the stress made me this late. I'm supposed to start with in this week but I've always had irregular periods. Now I'm worried I might be pregnant. Don't have any symptoms of any sort just really tired (but can be related to the built up stress, right?) maybe. Well from what the app says I'm 27-28 days late. Question is, when can I take the test? Isn't there a specific day for an accurate result? I highly doubt that I am but there's that what if....

Second question, my spouse and I have decided to not keep the baby. I know there is a pill that can be taken to help. Can that be store bought? Do I have to go to a clinic for it? Is a contraceptive pill the same thing? Can I take x amount of those?

TIA💝