Texas, it sounds like your parents (Mum especially) are having trouble letting go of "their little boy" and accepting you as you are - a grown adult man, who is perfectly capable of running his own life without their constant attention and input.
Why? Hmm...does your Mum work? What does she occupy herself with (hobbies, interests etc)? Do you have any other siblings?
I would guess that subconsciously she recognizes you are old enough to make your own decisions and run your own affairs, but deep down resents the fact that she now feels 'obsolete'. It's a total power play, and it's unfair on you at the moment.
I suggest riding it out, whilst demonstrating exactly how capable you are of taking care of yourself without being facetious about it. Try and establish some common ground, and build a functional adult relationship with your parents. DO NOT bring yourself down to their level with petty arguing and bickering, because in some ways that will justify your parents actions (even though they are the instigators here). Just remain calm and rational and in control, explain your actions and their justifications and re-dictate the terms the relationship works on.
And remember - being happy is a choice and a state of mind that is independent of your situation and surroundings!
/ramblings