Contract Binding?

I made an offer on a house and signed the agreement and faxed it to my realtor. I have not received the contract back signed by the sellers. I only have my agent's word that it is signed. I still have the original contract. Am I legally bound to this contract without the original being signed? What could happen if I backed out of the deal without the original being signed? Would it still be legal to do? Would I lose earnest money?

Thanks for your kind advice.

[HomeGuru]

Talk to your Realtor as I have no idea if the acceptance date has passed etc.
Get on the phone and demand that your Realtor give you the contract today or else.