Has anyone switched formula brands? My little one is almost 7 weeks old, and I have been supplementing with formula since she was 2 weeks old. Currently we are about 75% formula and she has a BM every other day, but our pediatrician said not to worry about it unless she acts really uncomfortable. She has been spitting up more and is really gassy in the last week, and I'm thinking of trying Gerber Soothe. Am I worrying too much?