Sorry if this has been asked before, I could only find references to before your period.
I had my first proper period after coming off the pill, which lasted 3ish days. A couple of days later (today) I have light brown spotting when I wipe and lower back pain. Is it possible I could be pregnant even though I had my period? Also, when would be the best time to POAS? I presume today would be far too early? 
Thanks.