Had baby oct 29th started depo-provera dec 13th jan 5th i bled till the 19th then the 20th had brown discharge now pregnancy symptoms could i be pregnant?

Take a test: It's possible you're pregnant. If you conceived more than about 2 weeks ago, then an over the counter pregnancy test should be adequate. If the test is negative then you can feel reassured. It is very unlikely that you could have conceived after the Depo-Provera injection. Also, irregular bleeding is the most common side effect of depo.

Vag bleeding: Depo Provera (medroxyprogesterone) is known to cause irregular bleeding. Whether you are pregnant or not - hard to tell. Most likely not if you've had a bleeding and then discharge, bu if in doubt, do pregnancy test.