Re: Love my moby but hate the becco
SSC (soft structured carriers like the Beco) fits are like jeans, what works on one body shape may not work on another. Do you have a nearby babywearing group where you could try some other brands of SSCs (ergo, Boba, kinderpack O&A, dream carrier, angelpack, bamberoo, kanga, and there are a few others) and see what works? They all vary in padding, waist shape, strap angle, etc and so can feel very different.
If you love the Moby definitely try a woven wrap. They won't sag like a Moby and can also be used for back carries (not safe in a stretchy wrap) as babe gets bigger. Dolcino, Storchenwienge, Vatanai, and Hoppediz are all good all cotton newborn to toddler wraps.