There's no getting around the extra 50 lbs since the last time you rode. Your legs are probably a little weaker now as well, meaing less of that weight is carried on the pedals and more on the seat. However, it does sound that the saddle is compounding the problem. Rather than spend money on new saddles until you find one you like, see if you can borrow a few from friends and try them for a day or two - just to see if any make a difference. Also try modifying your seat and/or bar heights a hair either way. Sometimes little things can make big differences.

Be wary of specific saddle recommendations as what works for one person doesn't necessarily work for another.