So when he goes potty at night, is it on the pad since he has access to it? If so, that's correct. He's WAY to young to expect him to "hold it" all night long and I think you have a great set-up there
. Alot of people have to get up in the middle of the night to let their puppy that young go potty, so I'd keep it the way it is, that's great. My bother and sister-in-law's Shih Tzu pooped IN their bed once when he was that young
After that she took my advise and crated him over night lol.
Once he's older (maybe around five months or so) try closing that area to the pad off for one night and see how he does. They usually just get to a point naturally by about 4 or 5 months old where they'll sleep all night and not even get up to go.