Hi Megan, I started gaining weight when I started the insulin.
I realised firstly it was because I had a lost a bit of weight when I finally got diagnosed and secondly because I was eating a drastically low calorie diet (was low carb but wasn't upping protein/fat so over my calorie in take was low). Also, with a lot of hypos I got in the early days, it left me famished so I was eating more at my next meal...
Basically I look at calories, as well as carb and I've started up the exercise and even in 2 weeks I lost an inch off my waist!
As long as your sugars are well controlled already, and you're confident with carb counting etc, it's time to look at the actual amount of calories your eating vs what you're expending.
Are you doing any exercise? I find that lowering my calories and doing exercise is the quickest way to drop the pounds (obviously and additional challenge to Diabetics, but one of those things). I know some folk advocate lowering carbs but for me I keep at a moderate level for me, although I rarely eat pasta, I do have maybe about 50g worth of rice every few days in an evening meal.
It's probably the evening meal that's the heaviest for me and most calories, I try to bulk up by throwing on loads of veg, lower calories and healthier. I also don't really snack too much, like you, although yesterday afternoon I couldn't resist 5 Rolos...hardly a sin to be honest considering I avoid chocolate for weeks at a time!
I need to watch my fibre too - I suffered from IBS a few years back and I wasn't overweight, so don't what the doctor is on about there! Fibre, is the one thing we tend to overlook really and if you're susceptible to constipation you really need to have a look at that, from what you've written, I don't see much fibre there am afraid. Add in plenty greens and if you want to keep it simple, see if you can get Soya bran (Holland and Barret), very low carb and high fibre, if you can chuck some on yoghurt or porride or juice - or get some Fibogel packs - with fibre you need to drink more water too!
The trick is keep a record for a week and be truthful. Then take measurements of your upper arms, thighs, hips and waist and set (realistic goals and dates - e.g 2 inches off waits in 6 weeks). Then start to bring in some exercise, walking for 20 mins 3 times a week will really help as a start if you do no exercise.
Hope this helps