I never found out with DD, they only did 1 ultrasound and they couldn't tell. Back then they didn't do lots of ultrasounds, usually 1 and then if no problems then none after that. With DS we had several ultrasounds and it was quite obvious from the very first one that he was a boy.
Both ways were fun...although it drove me crazy not knowing...it was fun to have the surprise when she did arrive. With DS the excitement and wonderment was kind of missing...but it did make it nice to know what sort of clothes to buy.
I had a lot of leaking with DD from about 5 months on, but absolutely none with DS.

I can remember having to buy nursing pads and wear them the last few months. There was one brand that had plastic on the back, so they didn't leak as much.