The test strips are nearly useless. You need a K-2006.
Small pools are more difficult to care for than large pools because they are more reactive and have a much high bather load. You really need a K-2006.
Adequate sanitizer level must be maintained to prevent disease transmission.
If you haven't added any dichlor, trichlor(tabs), or stabilizer you have no CYA. You need some - without it all the chlorine is lost in a few minutes of sun.

Have you found the Super Simple recipe? If not - log out and find it in the Intex pool care forum.

You can buy small amount of (expensive) dichlor at Leslie's if there's one close.

You really need a K-2006, find a link for it in the chlorinating / testing forum. It is almost never sold in stores, order it online.