Allah does not place a burden on us greater than we can bear. If the answer to your du`a’ has been delayed, it’s because Allah KNOWS you can handle it. He tests those whom He loves, so keep asking and remember that Allah makes with hardship ease. And remember, as with tawakkul, we need to exert effort as well.
Ibn Mas‘ud (radi Allahu ánhu) used to swear by Allah that no servant expects the best from Allah – Most High except that Allah gives him the best!