Well, I'll tell you what I eat each day and some of the things I do to "snack" when I feel the need to in the evening. I don't have any snacks during the day.
Morning: 50g Jordans Country Crisp Chocolate ( a bit naughty as it puts me on the limit, but.., otherwise it's fruit 'n' fibre or bran flakes)
Lunch: small brown ham salad sandwich during the week; weekends tend to be something like a sausage or bacon sandwich or soup. Careful with sausages for hidden carbs - you need a high meat content to be safe.
Evening: varies, but a staple at the moment is salad with some cold meats and a jacket potato
Evening treats when I "need" - max one a night: Options Hot Chocolate drink, 5 jacobs high fibre cream crackers with marg (sometimes some cheese), 100g(max but usually 50g) peanuts... people will tell you other nuts are better but they're the only nuts I like.
My advice would be to make small changes rather than a radical reducution... much easier to maintain that way. Perhaps start by having one slice rather than two and see how it goes. I think your body gets used to the volume of food and complains when it doesn't get what it's used to, rather than complaining when you actually need food. I'm not saying it's easy path, but small steps at a time can make a big difference.
David