First, you should test the battery with a battery tester that is capable of putting load on the battery.
Second, your not going to read amperage in a ckt. if you are not drawing any current. Take a simple ckt. with one bulb, a switch and a fuse. With the fuse removed you will read voltage on the live side of the holder. On the load side of the holder your not going to have any reading at all because you broke the ckt. by removing the fuse. With the fuse in place and the light not turned on, your going to read voltage only. You will read voltage up to the open switch, but you will not read any current because the light is not on to draw any. With the light on, you will read full voltage up to the bulb and on the other side of the bulb, you will read zero. You will also read current on the ckt. because the light is now on drawing current. To trouble shoot a ckt. You have to know how the ckt. would normally operate. You would check the ckt. at different points to check for voltage drop and would need to know if a voltage drop should occur at that point from any resistance or current.
I would check the meter on a known good ckt. To make sure the meter is working properly and is being used properly.