As you prayerfully try to find an answer to your question, remember this teaching from the scriptures: when we join the Church, we "are no more strangers and foreigners, but fellowcitizens with the saints" (Ephesians 2:19). This means we should be friendly to everyone at church. We're all children of God trying to worship Him in love and unity.
Here are a couple ways to feel included:
Get to know people of all ages. In sacrament meeting, for example, you could sit by a single mother with young children. She might appreciate the help. Or you could welcome and get to know members who are new to your ward or branch. When 12-year-olds come into Young Men or Young Women, you could sit by them. It's fun to have friends your own age, but if you reach out to others of different ages and interests, you'll have more chances to develop friendships.
Attend your ward or branch activities. It's hard to go alone, but you will make some friends by attending. Sit with someone who is sitting alone. Say hi and ask about his or her interests. That might be the start of a good friendship.