I have never edged so long that I did not or could not cum. And I edge quite a bit.
Like others here have stated......there are times when I have been edging for a long time.....on and off over several days....that I will often "leak" a partial load of sperm without having an actual orgasm.....not a huge amount, but definitely more than I get with precum.....everything is feeling wonderful and pleasurable, and the sperm just kind of flows out.......really can't control it........And like others stated, I normally stay hard throughout, don't lose the edge, and can keep on edging for as long as I can stand it......and when I do cum, the load is normally a full load....and does not seem to be "diminished" because of the previous leakage......hope that makes sense......
I think everyone's body is different........and you shouldn't be worried. I have had orgasms without ejaculation.....but its been because I'm sitting on a thick dildo deep inside my ass, which prevents the sperm from spurting out. It just means the sperm was "pushed" back into your bladder.....which is then discharged when peeing. Hope this helps.......