I have an 18 month old and a 4 year old. I am 18 weeks pregnant and I am still breastfeeding dd2. I am like a zombie some days, I just don't sleep well on my side. My bladder must be pea sized, seriously how can I go wee and then need to go again 5 minutes later?!
Dd2 is a climber and very adventurous, but at least still naps. Dd1 talks incessantly and no naps, at least she starts school in two weeks.
Having done this once before I would say pick your battles carefully. If they pick at snacks all day instead of meals they will still get what they need.
Get out everyday if you can, find a playgroup or children's centre with helpful staff who can run after your toddler. Use reins, go for walks, even puddle jumping on rainy days is a good way of burning off their energy.
Use CBeebies and dvds and don't feel guilty.
Have a special box of toys that they only get to play with when you need a rest. Also useful for when the baby arrives and is feeding.
If they tantrum at home provided they can't injure themselves, ignore, leave them on the floor, save your back.
If lifting onto the swings is difficult try sideways off your hip rather than bending forward or get friendly with other mums who might help you.
Teach them to climb into and out of the buggy and the bath (using a step stool), I had an EMCS with dd2 so couldn't lift dd1 afterwards at all.
Get rid of the cot side and get a bed guard so you don't have to lift them out, dd2 has been in a toddler bed since she was 16 months old, she soon got over the escaping escapades.
Borrow a friends older child or older cousin who likes little kids to play with them as often as you can to give you a break.
Pilates and gentle pregnancy yoga exercises are good for the back, hip and pelvic pain or a physio referral (although by the time you see one baby might have arrived if you are quite far along).
I found a mattress pad really helped with the hip pain at night, memory foam is brilliant stuff.
Soon we will be moaning about sore nipples, cluster feeding and the joys of toilet training while trying to feed a screaming newborn 