OK. I am 24 weeks, and have put on a stone and a half. I was overweight to begin with. I only know how much weight I have gained as I had my weight taken in alongside some extra tests in the week.
I know that it's hard - but STOP weighing yourself. This is the one time your body absolutely needs to put on weight. Throw out your scales if need be. You might be putting on more weight than others because you need to - your body is building reserves which you need to nourish your baby, and to get you through your labour and the first few weeks after the birth.
Your weight isn't usually checked at routine antenatal appointments so it's not necessary for you to do it. If you are concerned given your past problems then please speak to your midwife, because you need to make sure that you're taking in sufficient nutrition for you and your baby.
The advice to put yourself on a 1000-1500 calorie diet when you have a newborn has left me
to be honest. It takes 9 months to put the weight on during a pregnancy so you should allow at least that to get it off again afterwards. These celebrities who snap back into shape after having a baby generally are on very strict exercise and diet regimes which aren't necessarily healthy. There are a few women who do naturally spring back within a couple of weeks, but not many.
If you choose to breastfeed your baby then you'll need to be taking on more calories than you would normally in order to keep yourself going. Your milk production should be OK even on a low calorie diet, but you yourself won't be getting any nutrition.
The stress and pressure you will put on yourself in trying to not gain 'too much' weight or to lose it all very quickly after the birth is going to be far more harmful to you and the baby than the actual weight gain itself :(
Please, please speak to your midwife about this. She should be able to give you advice about what you should be eating and how much weight you can expect to gain (and remember, up to 1 1/2 stone can be just baby, placenta, and amniotic fluid which is lost almost immediately) or she can refer you to someone qualified who can.