Hi Kelsie - I could not have put it better than everyone else. We all start to blame ourselves when we lose a baby asking the usual "what if..?" questions. I think you have done a grand job in helping your queen to raise them thus far.
Try to look on the positive side. You and your queen have come through the experience. You have 2 lovely snow spotted and 2 sweet little brown spotted bengal kittens. They are doing well and are looking lovely.
Not going to preach so will just send a nice warm Cyber Hug and best purrs ((((Kelsie, Lily and her four little babies)))))