Tummy sleeper question

My almost 5 month old has been sleeping in her crib for almost a week now, and a few nights ago she started sleeping on her stomach. She never did this in her bassinet. I’m a nervous wreck and have went into her room a few times a night turning her over but then she just rolls back over and sleeps so good. If you have a tummy sleeper what are so things I need to help ease my mind. She has a zen sleep sac, but if there’s a better one out there for tummy sleepers I’m all for it. Thanks