Ammonia levels won't drop to 0

So I have had my tank for about two months. My ammonia is always between 0 and .25. Nitrite has always been at 0 and nitrate has been about 5-10 ppm. Did I not let my tank cycle fully? I do weekly changes at 20%. Should I do higher water changes or more frequent? I am using RO water that I get from my lfs. I use API master saltwater test kit. I have three damsels and 8 total snails.