I'd also guess it a combination of your timing being off and one of consistency. Make sure you are putting your thumb and fingers in the ball the same way, holding the ball at the same height and doing all the other pieces of the puzzle that is your delivery the same way all the time. One they are all the same it should not be hard to get a feel for your timing, IF you knew when it was proper prior to the problem.

This is one of the things we should do but we rarely do:
When everything is going right, think about all the steps and know what  they are and how they interact with one another. Know what happens and in what order it happens. Recognize how everything feels when it feels right. If you don't know that, you don't know what went wrong. Having a knowledgable person or coach watch you couldn't hurt either. So when something is wrong that you don't see, maybe they can. Friends are often not good for this, unless they have some degree of knowledge or are good at details.

--------------------
"Just because you can do something does not mean you should do it."
"No good deed goes unpunished."