Hi,
Army Reservist/ Personal Trainer/ Dad here - I specialise in pre & post natal exercise.
My wife had a similar experience with diastasis recti. She struggled a lot with jumpy exercises and walking long distances could sometimes feel a bit much - without going into too much detail!
Anyway your best place to start is actually squats. Yes, squats.
Since your stomach muscles are going to be fairly weak at the minute especially after two years, you need to be doing exercises that support you whilst working your core.
(Yoga and pilates are also a great place to start)
I'm assuming you know how to squat but when you squat tense your core and drive through your heels. It's also going to do wonders for your pelvic floor (but keep doing your regular pelvic floor exercises as well).
Moves like planks, reverse crunches (lay on your back, feet in the air and just crunch up and touch your heels), scissor kicks (lay on your back, hands by your side, alternate legs from the floor to straight up at a 90 degree angle) and suparamans (on all fours, raise right arm, left leg together then switch).
Walking, especially with the pram, and running (if you enjoy it) are also great at slowly rebuilding your core because you have to balance yourself and support your body. Just listen to your body and don't overdo it. Slow and steady is better than fast and quick.
Anyway hopefully that helps supplement your basic knowledge. In terms of DVDs popular ones out there are Davina McCall, The Charlottle lady from Geordie Shore (I don't remember her name sorry!), Gillian Michaels and Joe Wicks has quite a good progressive level HIIT DVD.
There are LOADS of Yoga and Pilates stuff on youtube - I've not had anybody really mention any, most people just go for youtube or go to a class so I don't know about the DVDs there sorry.
For iphone apps popular ones people have told me about (I'm on android you see) are Nike+ (available on android, I love this one but is mainly designed for running but has loads of coaching plans for beginners up to marathons), my fitness pal (tracks your food and exercises, suggests loads of things too) and carrot fit (the only one you have to pay for but has workouts on it).
Hope that helps.