Let me mention that breast milk is the best food for a baby and there can be no alternatives for the same. Most formula milks are cow milk based and hence difficult to digest. Since you mention that the child is on mixed feeds, it is likely that the vomiting is occurring in response to the supplemental feeds and not really to the breast feeds. Often children cannot tolerate such supplemental feeds and vomit it out. In case of cold, such regurgitative tendency often increases. Giving the child Domstal suspension 0.5 ml thrice daily before feeds should help in reducing such episodes. The other thing to be done is to try to increase breast feeding as much as possible as compared to the supplemental feeds. In case the vomiting still does not subside, please take the child to a doctor who can evaluate for presence of pyloric stenosis which may also be the cause of such symptoms. About your own feeding, remember that you are feeding for two persons and not one. Just take a healthy diet in increased amount and things should be fine. Animal proteins are essential and can be taken in the form of milk, curd or cheese.