Welcome to Thunder’s sondy, this place is awesome. :)
I don’t know about your scrotum leaping up when you stretch upward but testing for LOT isn’t that hard. All you need to do is give a nice firm basic manual stretch out starting at the 12:00 (straight up towards the bellybutton) or 9:00 (straight out) position and then as you continue to hold the stretch slowly lower the clock position by a half hour and do a kegel for a second or two. If you see your dick visibly tugback with your eyes then you have found your LOT. If not continue to keep lowering the stretch by a hour/half-hour until you reach the 6:00 position (straight down).
If you are not sure what a kegel I’ll quickly explain it. Whenever you take a piss try stopping the flow of urine. If you do that you are doing what we call a kegel. That is what you need to do what you are testing for your LOT.
Hope that helps.