Is my reasoning for resonance structures correct? given this picture, which resonance structure is correct? I'm thinking 1 and 3. You can't have 2 because the carbon which originally had a negative charge would be making 5 bonds, and you can't have 4 because the carbon on the right side of the new double bond would also have 5 bonds.  

So is this reasoning correct? I'm just having a bunch of trouble drawing resonance structures.
Well, your answer seems to be correct but not your reasoning. In 2 and 4 there are 2 extra pi electrons in the system which seem to have come out of nowhere. The best way to solve is to draw all the resonance structures and see which ones match with the options.