Yes, God certainly can use you and He wants to use you. Don't ever feel you are useless to God; no one is useless in His eyes!
Your pastor is right: God has given every believer in Christ at least one spiritual gift. Yes, for some it may be preaching the Gospel or teaching the Bible. But the Bible lists many other gifts as well, and God wants each of us to use our gifts to build up His people and extend His kingdom.
In fact, the Bible mentions some you may not even have thought of as spiritual gifts, and yet they are. It says, "If a man's gift is ... serving, let him serve ... if it is encouraging, let him encourage; if it is contributing to the needs of others, let him give generously; if it is leadership, let him govern diligently; if it is showing mercy, let him do it cheerfully" (Romans 12:6-8).
How do you discover your spiritual gift? First, ask God to show you what gift (or gifts) He has given you. Then examine your abilities and talents (perhaps with a friend's help), and commit them to Christ. In addition, look for some type of practical service in your church keeping the nursery, greeting people at the door, helping those in need. Often we discover our gifts only as we put them into action and then use them for God's glory.