Possibly...
The nausa would not normaly kick in till 4-6 weeks, but sore boobs are a sign. Not so much the boobs but more the nipples.
The cramps could be related to your cycle along with your back ache as a large percentage of women get back ache with their cycle.
Heart burn also is a sign, but again one that comes later its due to your uterus getting bigger and pressure being put on your stomach and in turn causing reflux/ heart burn.
The more you think about the larger chance you will make your self late and then think that you are pregnant, and if you are not you will only be more dissapointed when you find out you arnt.
Leave it about 5 days late till you test, if you really cant wait then just be prepared for some possible false negatives. Also.. Thoes tests aint cheap!
Best ofluck and let us know!