Generally speaking, we don’t believe it’s always possible or even necessary for believers to know their spiritual gift. First, none of the passages that explicitly list spiritual gifts—Romans 12:6-8, 1 Corinthians 12:8-10, Ephesians 4:11, and 1 Peter 4:11—seem to be exhaustive; in each passage there is a broader point than the identification of each and every gift, and the mention of gifts is merely to serve that broader point. Second, and more importantly, the New Testament’s expectation and exhortation is that believers serve wherever there is a need and wherever they’re able, knowing that God is at work in and through them to build up his people (1 Cor. 12:11, Eph. 4:16). The important thing is that if you see a need and you’re able to meet it, do so.
Some have said that God redirects our natural talents and abilities after conversion, and this is certainly one of the ways our spiritual gifts may manifest themselves. In practical terms, we might put it like this: what are you good at and what do you enjoy doing? The answer to that may be an indication of what your spiritual gift is, though, at the very least, you should feel all the freedom in the world to look for opportunities to serve in those areas, and then serve with a clear conscience and a thankful heart to the glory of God.