Colliehauler's advice is best. Go at least one large RV show, maybe more if practical. Look at all of the TT models available. Once you pick out a few that seem to fit the bill, try to go to a dealer and just sit in them, move around in them, do a little pretend stuff like moving about while someone tries to cook, pretend shower, etc.
Only this way will you have a pretty good idea if a floor plan will work for you.
And what works for some, does not work for all. For example, we have a Jay Flight 23RB which does not have a slide. It is 23' 4" inside the living area. But it works fine for the two of us. I haven't been tempted to go bigger. Haven't seen another floor plan that causes me to consider trading.
Other couples might be claustrophobic in such a small area. Just depends on what you like and can get used to. I'd say any trailer under 30 will feel small to you since you're coming from a MH.