Hi Thistle. I recently did what you're doing. I started with revamping my work capsule and just recently moved onto the casual capsule.
I got a pair of the jag pull on jeans in bootcut and they're comfy and flattering. They have a very forgiving wide waistband.
I also got several pairs of NYDJ, a cobalt skinny ankle jean as well as a dark denim trouser jean.
I got the jags and NYDJ at Nordstrom. If you can get to a store, the clerks are very helpful. They know their inventory and after trying a few pairs and seeing what you like and don't like they can steer you quickly to find the perfect pair
After I knew I liked NYDJ I found a pair (actually, two) at Rack for 50% off (I rationalized it as buy one get one free, haha).
I also tried the Lucky jeans at Nordstrom but found them to have a much lower rise. They felt more juniors cut to me with a much lower rise. The Jags and NYDJ seemed more forgiving with their higher rise yet are still totally fashionable (in my book).
I also got a couple of pairs of jeans from eloquii by the Limited online but I find their sizing to vary widely from one jean to the next so it's really hard to offer advice.
As for the squishy midsection I am right there with you. If I recall, we have daughters around the same age and I also have a 4 month old so I can totally relate!!! Rest assured you will not look or feel like you're wearing mom jeans with any of Angie's suggestions