I pretty much weigh exactly the same as you OP. I was 70kgs when I fell pregnant with DS. I stopped weighing myself at 34 weeks when I'd cracked the 30kgs. I was unfit, barely moved, had a sedentary job and ate what I wanted when I wanted.
This time round I started at 74kgs and at 20 weeks have put on 4.5kgs which is spot on average and is leading to an overall weight gain of around 14kgs. I'm a stay at home mum now so no sitting at a desk. I also am not having a cheeseburger meal as a snack 5 times a week (as per #1), nor am I drinking a large choc Big M or choc milkshake most days of the week (also as per #1). I eat every couple of hours and make sure I'm eating "good" stuff. Cereal or toast with avo for breakfast, fruit, nuts or full fat yoghurt for snacks (I find full fat yoghurt satiates me more than low fat), a sandwich or roll with whatever I feel like for lunch, and a smaller portion size of whatever we have for dinner. I'm trying to stick to around 1700-1800 calories per day. For me that means I'm rarely hungry, filling up on good stuff and eating small portions more often.
I'm no saint though. I'm still having chocolate if I want it, I eat fish & chips occasionally and I've had Maccas twice. I'm also doing Pilates and walking several times a week.
I'm finding that for me, eating good fats is meaning I feel full longer and don't want as much. I'm also fairly tall so can carry weight reasonably well, but like you, the recovery from my csar with DS was awful and I'm also convinced it was the weight gain that led to Pre eclampsia that led to the csar. I'm trying for a VBAC this time so keeping my weight gain down is vital.