My suspicion is that you're in your summer milk, DeepSix, though agree with susan, that so much depends, too, on breed, as well as on how any given animal is being raised; I've discovered that not only each season, but each breed, even each animal, can make a significant difference, and it just takes time to get to know the milk one uses on a regular basis.
In terms of seasonality, if that's really at the heart of what you're experiencing, Pav had a really nice breakdown, I thought, of the "temperaments" of the seasonal milks. At the risk of redundancy, I'll repost it
Think of it like this. In winter, everything is slower and heavier. In summer, there's more energy, more activity, more growth. So in winter, the milk has more fat, it will be like an ox... solid, strong, and stoic. And honestly, a little austere. Not quite so much flavor. The curd, as a result, is going to be reluctant to let go of whey, be more ponderous, and really try to provide the most calories to everyone to make it through to spring.
In summer, everything is more playful. The milk is thinner, lighter, has fewer calories but is packed with nutrition from the grass, and has more minerals/vitamins because the grasses take up those minerals from the soil and the sun. It's eager to make curd for you, eager to let go of whey, and has a sort of ADHD where you have to be more gentle with it and coax it, because it has a somewhat mercurial temperament and needs a more delicate hand. Otherwise, it will run around and play the jester, making one a fool.
I think the milks invite us to have different kinds of relationships with it and with the curd. Winter milk and curd wants us to be predictable and hunker down with it for the long haul, and be firm and clear with our demands so we make it to summer. And summer milk wants us to put on a t shirt (and hair net), turn up the music, and dance. It wants a bit of flirting and romance because it's dead sexy.
Dancing is very active. So the cheese will be thinner
If you handled it gently, as you mention, and it's doing this still, I'd second Pam's idea - try using CaCl and see if that helps. The other thing I'd wonder, is if you're not simply making an overly dry curd (I don't know cheddar, so am only speaking from my gut, sorry) - but if perhaps you're overworking the curd, or otherwise encouraging syneresis to an excessive degree, this, too, will obviously mean less yield. But I'd expect this more if you had a clear whey, and just more of it than one would expect.
You mention you got a cloudy whey, so a fragile curd does come to mind; though you handled it with kid gloves, it might need a gentler treatment still; in tandem with CaCl addition.