We've worked out a system that seems to mostly work for us.
All week long, we try to keep on top of the dirty laundry - wash during the day (we set the machine on the timer) so it's ready when we get home from work/school, either hang on line if dry outside or chuck most into tumble dryer and non-TD items go on clothes horse, dry things go into a large laundry hamper in the kitchen that only holds clean clothes/ironing. So if need be, it can be raided mid-week for "I need X" items
Over the weekend, generally Saturday early evening, we take that clean laundry and pour it onto the sitting room floor. Turn on the tv and find a reasonable movie, and all 3 of us (DH, DD10 and I) sit on the floor and fold it, it only takes about 10-20 minutes if we all do it, not that much longer if there are fewer around. 1 pile each for DH and I clothes, 1 pile each for everyone's socks/underwear, DD's clothes we tend to put into different piles per use (tops/tshirts, trousers, jumpers/hoodies, PJs, sportswear) to make it easier to put away straight to her room. DH and my clothes tend to go into the hotpress until we get a chance to put them away (roughly every 2 weeks).
Ironing gets thrown back into that hamper, and DH does that while watching Countryfile on Sunday evenings.
If you can't face sorting out the old things that don't fit - literally do it one step at a time. Do 1 drawer today. Then another drawer tomorrow. Take out things that definitely don't fit for giving away/charity shop/ebay/whatever. Put things that might still fit on 1 side of the drawer and clothes that are downstairs and definitely fit on the other side. When you've gone through everything, grab your DD for a session of trying on - maybe try and put the biggest and smallest of those out first and that may help eliminate a few things easily without needing to try them on.