Is this to much to eat on a diet?

Paige

So I started my diet today really well, I went to the gym this morning but in the afternoon I've found myself eating so much...

I've had:

.1 orange

.1 nectarine

.1 handful of strawberries

100g of pasta shells with 75g of tuna and 2 tablespoons of mayonnaise

.Cheese sandwich.

.Tiny slice of cake my brother made me try because he made it at school.

I feel so fat right now and like ive ruined my diet completely by eating so much. I just feel stupid and it makes me feel so guilty and horrible.