Great job losing the weight
Sounds like you've been left with the usual fatty deposits, which diets alone struggle to deal with. These are typically on ones bum, thighs, tummy or, as in your case pectoral region (chest/breast).
As you've mentioned you were previously overweight and have not mentioned any other symptom it's most likely the cause of the issue, rather than some sort of hormonal imbalance (if you have concerns pop along to the doctor).
Exercise is really the key here. I'm a little puzzled that you say, "when i start exercising". Start today with an extra 20 mins walk and a couple of press ups.
Sustainability is the key here - don't plan to be a gym bunny. Just plan to get your 10k steps with some simple toning exercises every day, try to thrown in and a couple runs a week. Do this for 6 months and you'll be right as rain. Joining any sort of sports club is a great way to improve too - does your school or institution have any sports groups that you'd be interested in joining?
Obviously you also need a healthy balanced diet but removing eggs and tomatoes are not an issue (this is dubious forum based advice and is about hormones, which doesn't appear to be the cause of your issue). I'd start with reducing, aiming to remove, sugary drinks, deserts, sweets, crisps and high fat foods. If you smoke or drink too much; stop. A diet is not the goal; sustainable healthy eating for the rest of your life is.
Track everything on myfitnesspal or similar application so you can stay on track and understand where you're going wrong.
Talk to your doctor before doing anything radical or if you have underlying health issues.