My breast sore and feels heavy every time I wake up but it's perfectly fine when I'm awake and doing any daily activity. It's been a month now since I felt this. Is it also a sign of pregnancy? I've done pregnancy test and its positive in my first try.

If the test says so then I would agree with it. There are more chance of a false negative then a false positive. Provided that you followed the test correctly. I don't think the sore boobs really play that big of a part of it. I would contact your doctor and get a referral to a OB soon.