Sucking in Water When Breathing

I took lessons when I was a kid and never mastered the breathing technique for freestyle swimming so I gave up on swimming. Now it is 30 yrs later and I am determined to learn how to swim and have been taking a group class at the local natatorium. I have been making a lot of progress and learning things that I don't remember from my childhood lessons (keep your chin to your chest, making the S-pattern during the pull stroke, etc). I have also been focused on rolling of the body more - and especially rolling to breathe so that my head is on my left arm/shoulder (breathing to the right). However, I'm still struggling with the breathing in that I am sucking in water and end up choking. I've had multiple people watch me and they say that my form looks good and even the part when I roll to breathe - but they are unsure at what point I am getting water in my mouth. It's been hard for me to figure it out - here's some of my thoughts - it's a bit hard to self-diagnose and so far the people watching are not catching it - Is the timing of the opening and closing of my mouth just a bit off that I am sucking water when I turn to breathe and return to face down? I'm not the best at exhaling underwater so I wonder if I'm trying to exhale and inhale during the short time that I am turned? Do I need to turn my head more (look at ceiling)? Am I slowly sucking in water when my face is down since I'm not exhaling correctly? Any thoughts on how I can figure this out or other things to look for? Thanks Mike