Hi Leanne, you could well be pregnant. Any changes in your boobs can be a sign and heartburn is something pregnant women suffer from, I suffered with it terribly in my first pregnancy (my son is 14) but this time around nothing so far, thankfully :o) At the beginning of this pregnancy I had a couple of very severe headaches too, I think its hormonal. I can understand that you don't want to do a test but I think you're safe to go to the docs now and tell them since you've missed two periods (will save you the money of buying them too). If you want to buy them, I used shop own brand ones (Tesco and Sainsbury's - did a few as couldn't believe we'd conceived so quickly!) are both very sensitive to the pregnancy hormone and they're inexpensive compared to the likes of Clear Blue and all those other branded ones. Good luck, hope your result is positive.
J