The way you had processed and dealt with your miscarriages was healthy and reasonable. Without sounding insensitive about the book, just because his belief system is that miscarriages become real children running around in heaven, doesn't mean he is right or that you should think the same way. And even if there is a possibility that his version of heaven is right, I don't think your children will be sitting in heaven wondering why you haven't been thinking of them all the time.
Life is hard enough without us heaping a pile of unnecessary guilt onto ourselves. You sound like a lovely person and if you do get to meet your angels in heaven one day then won't that be wonderful. But for now, I would carry on as you had been before you read that book.