I'm like you, thinking I'd love a thread cutter. Actually it's a pain in the neck (or should I say fingers?) I have RA and don't have much flexibility in my fingers so it's difficult to pull the threads up to start another line of stitching. Those short threads are probably bunching up causing those knots. I pull the thread out a bit and just cut the threads with snips, Then I have a length of thread to start my new seam.