You should definitely not hold off going to Israel for Yeshiva! I know of a number of Yeshiva boys and Seminary girls who did it very successfully. There's a woman in Yerushalayim who sells delicious homemade SCD snacks and frozen meals. There's also a big SCD center/support group in Bnei Brak headed by Rabbi Avi Cohen. He can be contacted at +03-703-123, or +052-765-6267. He should have the contact for the lady in Yerushalayim as well.
In addition to that, you can contact the cook in the Yeshiva, and have him pay extra attention to your needs, for example: whenever he serves chicken, he should prepare your portion without any breading/coating, just plain spices. Same with fish. He should also make sure there's always plenty of soft/hard boiled eggs, fresh fruits/veggies, etc.