You said the fronts were measuring 4 inches wider than called for. Is that each front? If so, yikes, that is quite a bit. Did the pieces measure that big before you soaked them? Did you block your swatch before you started and did it grow any? I confess I don't usually wash swatches, but some yarns can give you a nasty surprise if you don't (dirty little secret, I think they sometimes do even if you do block your swatch). If your pieces grew during washing I suggest you be very gentle with the washing and give a lot of support to the pieces when you lift them out of the water. Maybe it would be better to drain the sink and lean on the pieces to extract as much water as you can before lifting.
But have you tried Lucy Neatby's idea
of blocking the item out while it is dry and then misting it.
ArtLady is our resident expert at blocking. I think she blocks everything she makes and always gets such professional results. Have you looked through her posts about blocking?
I don't always pin things (often don't). I just blocked a sweater body for a fisherman's gansey (100% wool) for DH. I was wanting to pin it but didn't have any pins I was sure would not rust and this is natural colored and that would have been a disaster, rust I mean. I did a little measuring and stretched the length of the armholes a little because I was a little worried about that part being too short. For that I washed it, I did do the draining and leaning I mentioned. Then I put in in the washer on spin and spun it a little, but not full time because I've found that I can spin in wrinkles. Laid it out gently and patted it smooth. Did the measuring and slight stretching. Then waited for it to dry.
You might try redoing your sweater and coaxing it to be as small as possible.
It might help a little. But if your item started out the right size I think the dry blocking and misting might have helped it not grow so much, if it did.
This is a bummer. I'm sorry.