I have been having on and off nausea since about 5 1/2 weeks. I am 7W4D today, and I too worried about it. It comes for 2 or 3 days, then nothing for a few days. Very strange I know, but everyone keeps telling me its normal, and thats what all the websites on pregnancy symptoms say as well. Maybe you and I will just be 2 of the lucky ones who don't have it constantly. Congrats on seeing the heartbeat, that is such a positive sign, and also must have been such a beautiful sight to see!
Oh, I was just the same. I was so nauseated from about 6 weeks pregnant, with a few days here and there where I would feel much better, and then I'd get sick again. I think it's pretty normal. Your body is adjusting to the hormones and some days are probably just worse than others.
I'm 17 weeks now and still having good and bad days when it comes to symptoms!
Sheri