Hi Michelle,
I do know that what you are feeling to some degree is pretty normal even for those who have not lost a baby. When I came home from the hospital with my son a few years ago, I was completely paranoid about everything and anything happening to him. I would invent really stupid scenarios in my head about what might happen, for example, I was scared to cross the road incase a car came out of no where, and a really stupid one, I was terrified that a magpie would peck him as we had magpies out the front of our house. Just a few of the weird things I thought about and I eventually settled down and was not so bad. But now being pregnant again, I am really starting to worry about SIDS etc too. I guess you should do what you have to do to get through and if that means checking up on him every 5 mins, then do it. I hope you are not too stressed about it