Simple carbs, also called white carbs, the big five are:
Bread, potatoes, rice, pasta and sugar.
Cut them out, or down significantly and you will feel less hungry. Don't bother with brown pasta or rice, brown bread isn't great either.
Let me break down your menu from yesterday
bagel with cream cheese - I don't know how many cals...
Bagel - simple carbs,
Cream cheese - might have added sugar and starch if low fat
cup a soup - 65cal
Most likely contains potato and cornflour, both simple carbs
oven baked crisps - 109cal
Potato
Activia yogurt - 100cal (must be able to do better here)
low fat yogs are really high in sugar, you would be better of with FF greek yog and some strawberries.
banana - 90cals?
One banana is the equivalent of 3 teaspoons of sugar, think of it as a treat rather than a snack.
small pot of fruit ?
Hard to say without knowing what fruit but anything tropical is usually high in sugar.
Watch out for anything low fat, it is usually crammed full of sugar to compensate for the lack of fat in flavor.
Good non carby snacks - babybel, boiled eggs, pepperami/salami.
Lots of fruit is sky high in sugar, so stick to berries, and avoid anything tropical, for snacking you are better off with veg sticks, celery is nice with cream cheese or hummus.
Instead of having your ham salad in a pitta just up the quantities and stick it in a lunch box as a ham salad, can also be done with tuna, chicken, eggs, cheese etc.
You can buy pre boiled eggs in snack pots from most supermarkets now. As well as snack portions of nuts - like those whitworth shots.
Complex carbs come from veggies, pulses and some ancient grains i.e. quinoa and barley.