My beautiful Siamese cat is sick and not eating...T_T ? ?

Well I would like to start by saying that while i realize you don't want to go to vet due to cost, it is really the best option. For the time being, food and water are going to help. Try boiling a little rice and come chicken to eat. This is a bland diet and hopefully will be less nauseating for your cat. In addition make sure she is drinking water, we don't want her to get dehydrated. Check the little box, make sure urination and stool is normal. Keep an eye on her, and work on convincing your parents that taking your cat to the clinic is the best option.