Here is a simple hack,
Going to sound weird, but if your plant seems droopy, you think it has been over-watered. You can test by straitening a coat-hanger, round the tip smooth with fine sandpaper, so it doesn't tear roots. Then gently roll-n-push air channels slowly up through the container's bottom drain holes. Set potted plant on a fan, so that air --oxygen-- gets pushed into to the roots system. If it was is over-water, you'll see the plant perk up in a few hours. It will perk up really fast. Depends on pot size, a 120mm - 140mm pc fan (using a 12v wall wart) attached to a plastic pot saucer will give light air pressure to the bottom drainage holes. Make sure to remove fan before next watering. You'll have to water more frequently if you use this setup to oxygenate roots. If you decide to leave the fan for oxygen, put it on a mechanical timer, 30-60 minutes on; an hour or so off. Good to run it for a day right after a heavy water, if you suspect the soil is acting wet.
Sometimes a seedling mix can create a "wet center-ball" at the center of root mass (if too much is used); and even though you've transplanted into light and fluffy soil, with good drainage. Instead of drainage, the new soil insulate that wet-ball-from-hell and you'll get nutrient-lockout and a vicious cycle of over-watering. Where you'll think everything is nice and dry but center mass is soggy wet, strangling the plant..