After fort Hagen my dog has gone MIA. I've tried going to red rocket and ringing the bell doesn't work. He showed up at sanctuary when it was being raided but when I stopped him and asked him to join me he disappeared again. Also I don't get any options to talk to Preston anymore. He just spouts boring rhetoric or tells me about a settlement to save. I don't get the option for him to join me.

Dogmeat went MIA on me yesterday as well. Not sure where he is, he was my companion, then just disapeared without warning. Also, he took off with all of my good items I was storing with him...

Preston is not a companion, so no chance you can get him to come with you. He is the leader of the minutemen, he can't leave his duties. Maybe after you complete the minutemen quest line.

If I dismiss Dogmeat and send him to Sanctuary, he will be laying in a doghouse behind the first house past the bridge if you are walking into Sanctuary from Red Rocket. Took me a minute to find him. Check there. Maybe you were talking to him and hit "dismiss" and didn't realize it.

No I completely scrapped all of sanctuary before I started doing the first mission to fix it up. There are no more dog houses. He is just completely gone.