Hi Samantha,
There's nothing wrong with satisfying a sweet tooth with a little piece of chocolate (or whatever your weakness is) if you can stop after one small piece. Some ideas for sweet alternatives:
Switch from ice cream to a 1/2 cup of low fat frozen yogurt.
Check out the different yogurt (not frozen) flavors available - many provide the sweetness you want, while still being low fat and healthy.
If you like dark chocolate, it'd be a slightly better option. It contains flavonoids that help protect us against heart disease and some cancers.
Don't forget fruit, which is naturally sweet!
Sounds like you've trained your taste buds to crave something sweet after meals and any time you try to change habits it's a battle, but a battle you can win:) If nothing else, plan a way to distract yourself or keep yourself busy when you finish your meals until the craving has passed.
All the best,
Lisa Nelson, RD, LN
Tips to Lose Weight