Sudden nausea? Help!

I've tried to be better about tracking when Mother Nature comes to visit me and the last few months have been fairly regular, within 32-35 days. HOWEVER my monthly did not come like it should have last week.. I never had any real symptoms while I was pregnant with my daughter, didn't even know that I was pregnant until I was 24 weeks, so I'm not sure what to look for. The last few days I've noticed a nauseous feeling every time I smoke, not over powering.. this morning I had to pull over on the side of the highway. I have been wanting a baby so bad and don't want it to be in my head but I also don't want to get my hopes up.. Thoughts? Best test to use? Should I wait?