What could be wrong with my cat?

I have had my cat for over 2 years. She is the world to me. However, lately I have noticed that she has been shedding a lot more, and not very often but her whiskers have been falling out. not alot (maybe 1 or 2) but still. What could this mean? Please dont tell me to take her to the vet. I already know that I should and I am going to next week. but what do you think that this could be? I mean I did just recently adopt a new cat. Could that be the reason for her shedding more? or could it be her food? I feed her Purina One indoor formula as that is the only cat food she eats. If you feel it could be the food then please suggest a new food that I could get for her? Thank you.