Potty Training – Still No Result

My son is 2 in June he will be 3 and I have tried everything and he is still not potty trained. Am I pushing too hard. I dont think I push him but no matter what I say to him he does what he wants. He will use the toilet a few mornings and then nothing for days. I bought some briefs for him and even those are now getting small and he still isnt potty trained. I know he understands what I am saying and what to do but why no result??? I am tired of buying diapers.