The amount you are using is very low. Use more vector and gene of interest 1-2 ng of each ( I ng in one reaction system )  and then try to purify. Use 0.8% gel to run and cut the band and follow the next steps....In the last step use less water to elute it.

For your ligation  use less vector , more gene and for transformation make sure competent cells are ok . Good luck .

There could be problems during the gel extraction.

1. The gel might not have melted completely. You can vortex multiple time and melt at 50 degrees.

2. Load the melted gel atleast two times during centrifuge.

3. Give a longer free spin so as to take the ethanol out which suppresses the elution.

4. Keep the elution buffer for sometime in the column for some time before performing the centrifugation to ensure that most DNA came out. Also use less amount of the elution buffer so as to increase the concentration of the DNA finally.