So tired!!!

So I had what I thought was my period a few weeks ago. About three days after my period I had very light spotting(was not leftover period)... The past month or so all I want to do is sleep! I take almost 5 hour naps on the weekends (I've never been a napper!) last night I fell asleep around 10:30 pm and didn't even wake up until 1 pm the next day! I forced myself to wake up at 1 pm only to go downstairs to watch tv and pass out on the couch for another four hours! Here it is 5:30 and I can totally go back to sleep again! What is going on?! Has anyone ever had what they thought was their period only to find out they were actually pregnant?