Im 14 and 210 pounds but have IBS, and I want to lose weight, help??!!?

hey, Im 14 and weigh 210 pounds and 5"5....I really want to lose weight and become a normal weight. the problem is I have IBS, which means that I personally, cannot have fibre- wheat, whole grains, pastas, most fruits ect. I have to be very carefull on what I eat. Please help me with some tips on how to lose weight for the summer, I have school, loads of homework and too much study so I haven't got a lot of free time! I would like to lose 3/ 4 stone and how is that possible? thanks