@rfradette Thanks for reaching out!
The only difference between the DoubleNest and the SingleNest is the amount of fabric across the hammock, allowing the DoubleNest to be wider by 19" and thus accommodate two people laying down. If you plan on being in the hammock by yourself, the DoubleNest will give you a little more flexibility with the additional fabric (allowing you to 'wrap' yourself up a little more with higher walls, 'cocoon' style), but other than that you won't notice much difference. One drawback to the DoubleNest is that fabric can bunch up on the sides and make it a little more challenging to get in and out of or sit on sideways 'couch-style'.
You should be fine with the SingleNest if you're looking for a solo hammock for camping and backpacking (or just setting up in the backyard). There are lots of reviews of the SingleNest from folks who are taller and heavier than you that really enjoy that hammock. When your hammock is delivered go ahead and set it up and try it out. If you're planning on taking it backpacking then set it up with all your gear and see if you are comfortable. Any day you have an excuse to product test gear by taking a nap is a good day!
Hope this helps!