Hi, Lynn. I suggest that you go to an independent dealer for a major paint company and talk to them. Unlike the "big box" stores, they will listen to your requirements and present situation and suggest a paint that best fits your needs. You should also ask about how to prepare your walls (washing, etc.) and how to prime them.
A good paint job is 75% preperation and 25% painting. Preperation includes buying the best paint that you can get for your needs. If it costs you $20 more for paint that will last you 10 years instead of 7, it only costs a few bucks more a year. Paint companies formulate paint differently for "big box" retailers than they do for theirown paint stores. This is true even with the same brand name and company. The low price that you get at the "big box" retailer does come with a cost for you. And you should get the added benefit of having someone knowledgeable to instruct and guide you if you shop with the small retailer.