Those plates that are sectioned into vegetables, protein and carbs are great, it helps you with portion control and maybe your DD will be less likely to ask why she has more veg and less carbs on her plate.
There's lots of healthy options, eggs are always a good option for breakfast, high protein, should keep you full. You could make an omelette with lots of vegetables in.
I have a personal training qualification and I used to be really into the gym / dieting.
The best thing is to not restrict yourself, for example, if she loves chocolate, let her have 2 giant chocolate buttons on her porridge in a morning. They will melt so it looks like there's more, and you've had your chocolate fix but it will be about 20 calories worth.
For lunch, wraps with tuna / chicken / ham. Or those sandwich thins are good for lunch boxes! Apples, Greek yoghurt, popcorn all make for great lunch time snacks.
You could get the snack sized treats, like the mini bags of malteasers ect that have about 80 calories in, for times when she wants a treat!
For dinner, basically make sure you have a good source of protein, chicken, salmon, beef ect, with veg / salad and some carbs, rice, pasta, sweet potato ect.
You don't need to do things to the extreme, for example if you prefer white rice to brown rice then have white rice, usually the difference in calories is minimal anyway.
Look out for the sugar content in things, some yoghurts will be advertised as low fat ect but have ridiculous amounts of sugar.
Do lots of exercise without saying 'we need to do exercise'. Lots of nice long walks in the summer, swimming as you have already said! What about trampolining? You can go to those jump places and pay as you go. Dancing maybe?
Good luck OP xx