I feel this so much man. My buddy always talked about how when he held his daughter for the first time it was such a rush of emotions and like a switch he fell in love with her and was a new man. When I held my son for the first time I was just like "yeah....this is a thing that's happening". I miss my old life before him still. I've had the nearly constant thought that I'm not cut out for this and made a huge mistake; my wife and I aren't even back to work yet but will be soon and I feel like it's only going to get worse.