Especially when you're new to bow making, you should not trust the moisture meter in bow making. It is such a tricky device that requires skill and know-how. Very, very few bowyers rely on this piece of equipment alone to make their decision whether a piece of wood is dry. It always measures the surface of the wood. So you need to measure freshly exposed surface to get a somewhat decent figure. But still.
It's better to weigh the wood accurately (to the gram at least) every now and then. If the stave has not lost any weight (equals water) for at least a week in a row, it will have reached EMC.
If the stave was cut in fall, it may have dried a bit, a lot or not at all. Depends on many factors that you didn't yet clarify. How big was the stave since fall? Where did you store it; outside, cellar, in a hot box? When was it reduced and to what dimensions? Was the stave sealed and/or did you leave the bark on? All these factors influence the drying speed of the wood.
A quick answer to your questions: the oak has probably at least 14% moisture left. Since it has been drying for at least four months, it has probably lost a substantial amount of moisture. It should be dry enough to not start splitting and checking now, but it is not dry enough to allow you to bend it. Reduce to near floor-tillered dimensions, and put to dry for at least another month indoors where EMC will be around 9%. Monitor moisture loss by weight loss.
