Pregnancy Symptom?

My nipples have been itchy for the past few weeks. Lately they seem to be even more so. I live in Michigan and the temperature has been really low so could this be a pregnancy symptom or just dry skin? My periods have been really out of whack, too. I'll bleed heavy for a few days, then I'll stop and start back up the next week, but I've been in the clear for a couple of weeks.