M.M.
M.,
I think you are doing a wonderful job and need to not worry so much about your son. If his father is away more than at home right now, he needs the comforts of his mommy's arms. Children carry stress much differently than we do. They are unable to process it and sometimes it shows in developmental milestones. Maybe your son is making a statement with the potty training. Mommy, I am not ready to grow up. I need to be held and told everything is going to be alright. Maybe the best thing you can do in order to push him over that last hump of ditching the diapers is to absolutely hold him and sing to him during the day. I mean really hold him and love on him. Tell him that he means the world to you. Tell him that Daddy thinks of him all the time and can not wait to see him. Tell him Mommy absolutely loves spending every waking moment with him. Tell him all the most wonderful positive things you feel about him. Then, keep putting him on the potty for sit time. Don't force it, just give him every possible opportunity to sit on the potty throughout the day.
Again, the needing Mommy because of underlying stress could be causing the sleeping by self more difficult. My son is 28 months old and he sleeps half the night in his bed and half the night in ours. This does not bother my husband and I. We are sleeping anyway and by him sleeping in the early mornings we all get a restful sleep. If you want to transition him to his room, just keep putting him back in his bed over and over again. It takes about 2 weeks to a month in order for them to finally get used to the new sleeping arrangement.
Hope this helps.