Inconclusively means “in a way that does not lead to a clear decision or result.” A game may end inconclusively if there is no winner; talks may end inconclusively if nothing is agreed; two studies may come out inconclusively if they point in different directions. It is the adverb from inconclusive, and it belongs to the same careful, rather formal world — reports, news, science. Though actually, it is not the word for “I am not sure.” It describes how something finished, not how a person feels.