I'd go through and sell the stuff you didn't like or anything that didn't get worn, etc. Then hold onto the usable stuff until after baby gets here and you know for sure you need pink things :) I think the dr and ultrasound are usually right but I admit I always had boy and girl names picked out just in case!
In my experience, after my first, I realized I had a lot of things I didn't need/didn't use and then our second was a girl. Now as DD grows out of things I get rid of them because we don't plan to have another. But if things change - I would buy simple basics and stay on top of the laundry,LOL! Don't know if you were planning on selling at Once Upon A Child if there's one by you but you can also get some items there too, if you did end up having #3.
Congratulations and good luck!