One more thing I can think of to tell you for now, since you can't feel anything when palpating. Grab the snake near the head with one hand, and the other hand on the tail below the cloaca. Stretch the snake out as straight as you can get it, holding the head skyward. The flip the snake such that the tail is pointing skyward. While doing this, watch the belly closely. You should be able to see the eggs very easily (matter oif fact you can count them if you look close enough). Now, flip the snake once more, so that the tail is pointing to the ground again. Watch the belly again closely. This is the important part. See how close the egg gets to the cloaca. If your snake is indeed 3-4 months post ovulation, that egg should get within an inch of the cloaca. If tyhe egg stops a good distance from the cloaca, then you could potentially have a twisted oviduct. If it gets close to the cloaca, but looks very large, then there is a possibility that the egg will need to be aspirated as it is too big to pass (with that said, a snake's cloaca is pretty stretchy, and can get rather large: similar to a human giving birth). So, I think the twisted oviduct is probably the culprit in 90% of the Ball Python Egg Bound instances.

I hope that helped,