While fruit is really good for you, it is high in carbs, so limit your intake to 2-3 serves a day. Veggies likewise are great for you, but avoid high intake of carby veggies such as potato, corn and sweet potato. Still eat them by all means, but don't have a big dish of mash potato or a huge cob of corn.
My first thoughts are that you aren't getting enough protein. Fruit and veg doesn't contain a whole lot of protein, and meat is the easiest source. So if you have a good 150grams of lean red meat, chicken or fish, that will give you a nice hit of 40grams protein.
Wholegrain carbs are good for you and a wonderful energy source for when you exercise, but with anything, all in moderation. It is best to have your carbs earlier in the day, such as a bowl of mueslie (read the labels because some aren't good, try and find one balanced in both fat, carbs and a good fibre level) and avoid heavy carbs for dinner everynight. Wholemeal pasta, brown rice etc are all good, but only a few x a week.
I don't think its a good idea to drop under 1600 calories, you're a young man who is exercising so I think any less and you wouldn't be getting what you need.
A great tool to smash a plateau is to mix up your exercise. What are you currently doing? Add in something new a few times a week, be it a bushwalk, gym class, martial arts, swimming laps etc...keep your body guessing and thinking rather than letting it get too comfy.
Try not to eat past 8pm, drink plenty of water (a good 2+ litres a day) and get at least 8 hours of sleep a night.
If you're doing all of these things and still no help, a few sessions with a personal trainer might help you out, i'm sure they have dealt with many a plateau!