The hammock was not your problem I use the same one in the summer it is the same as the Eno doublenest! Use your sleeping bag as a topquilt and get a good UQ! Down!
Make sure your distance and angle is right and you should get a good flat lay as long as you lay at an angle! If you want to use your thermarest let all but a little air out and you will find your sweet spot eventually! Good luck!