I was out in my HH at the weekend as well. Snow, rain and cold weather but I was toasty warm and dry but I was using two nanok sleeping bags and a full lenth mat, not to mention the hex fly. I do have my doubts about a 3/4 mat.
Had to get out twice during the night to answer the call of nature. Funny how in these circumstances I am much quicker at getting back into the sleeping bag.
I am surprised your hammock was rocking as much. One of the things I was most surprised at was how stable mine was. Did you have it pegged fairly tight?