Hi Patrick and another hearty Welcome to Chordie!
Russell's got you on the right track for sure there! Another thing that might be helpful, is to try to get your thumb as close to the center of the back of the neck as possible (even if it means getting the neck into a more upright position, like classical players).
There will be times when you will need to wrap your thumb over the top, but for the most part it is easier to get around the front and straight onto the strings with the thumb in back. Once everything falls into place and you develop "finger memory" then you can relax your stance. It is more important to play cleanly the chords you know than a whole bunch of unusual ones that don't ring true.
Practice, practice, and patience..... you'll be surprised how quickly you progress.
Once again Welcome!
Take Care,
Doug
"what is this quintessence of dust?" - Shakespeare