Hi, here are a couple things I suggest to my ladies:
Firstly, start now correcting your posture. Stand, tail tucked in, back straight, tummy (if you can in) and shoulders back. Best way to start practicing is against a wall.
Not sure if these exercise will make sense but you can try the following:
cat stretches: position yourself on all fours, on the inhale, arch yor back like a cat, head down and then exhale going back to neutral position,
pelvic tilts: lie flat on the floor, legs bent at knees - on the exhale lift your pelvis a couple of inches off the floor, hold and release,
spinal twists - you can do this either seated or lying down - cross one leg over the other and turn in the opposite direction.
I would also suggest a swiss ball - it's great for easing lower back ache and building core strength.
Oh, and remember your pelvis floor exercises!!
Hope these help you.