outdoorbr0, your first post, welcome to the forum.
First off, just to be clear, do NOT use a narrow cord like a Whoopie Sling directly around the tree. I'm not saying you did that; you did say "strap" not "cord". But here are three reasons why not to use cord:
1. If the tree has "tender bark" like some trees back east, the cord will cut the bark, and I've read this will damage the tree.
2. If the tree is like our PNW cord-eating Ponderosas, with the cord under stress, the bark will cut through it like a hot knife through butter.
3. Every official "campsite" location I've seen, if they allow hammocks at all, require at least a 1-inch strap; some require at least 2 2-inch strap (a DIY project using old car seatbelts). Some require something inserted between the straps and the tree - like a piece of camping CCF pad, towel, or twigs placed vertically between the webbing and the tree.
It's good to have a suspension kit that works everywhere.
For the quickest/easiest, I'd use Daisy Chain. The stuff from ENO and Kammock is a bit heavy and the loops are spaced about six inches apart. The daisy chain from DutchWare is lighter, and the loops are only about three inches apart, for a finer adjustment. The only teensy downside compared to ENO's Atlas straps and Kammock's Python Straps is the lighter Dutchware loops are a little bit - just a little bit - more difficult to slip a carabiner into.
If you go with Atlas or Python straps, find yourself a six-inch Amsteel loop you can fold in half. Fold it in half in the daisy chain loop, and you'll have a 3-inch step.
For continuous adjustment, you have your webbing and cinch buckles solution. I may switch over to them for a change of pace.
But it sounds like you have two other issues. First, knots? Where are you tying the knot? If it's the webbing around the tree, usually you can just fit the tail of the webbing through a loop that is usually sewn at one end. Or you can use some sort of hook - smaller carabiner, evo loop, etc. Because I don't know where the knots come in, I'll stop there.
The second issue is "getting the tension right". Does your hammock have a ridgeline? If not, MAKE ONE
First, set your hammock up so it's just right. Then measure the distance, end-to-end, of the hammock that gives you the perfect sag for your diagonal lie. Then make a cord of that length and attach it to the hammock ends. This process has already been described in previous posts. That ridgeline cord is your "yard stick". You string up your support so the ridgeline is just snug and the hammock is at your preferred distance off the ground, and you have nirvana every time, without the trial-n-error. If your ridgeline cord is made of small amsteel - like LashIt (2.5mm or 1.75mm) you can leave it attached to the hammock while you are in it. If it won't hold several hundred pounds without stretching (no paracord), put a clip on it like a small S-biner and remove it before you get in the hammock.
