Run a tank of fuel on the ground and time it.
That said, and I know you don't want to hear it. If you have access to an instructor swallow your pride and get one.
I tried it on my own because I was having trouble finding some help. 2 stupid mistakes later I am on my second trainer already, I got about a dozen flights with the first one. I am repairing it but it is a major rebuild.
What did I do? The first crash was caused by the aileron servo tray coming loose after my hard landings. A good instructor would have caught that I think.
The second was I forgot to raise the antenna after range check. I think if an instructor had been present he may have said what my signature now say's.
Anyway, I now have found a kind soul to come out and spend some time with me on the buddy box.
Which ever route you go good luck and happy flying!