When you go to your different activities, keep your eyes open for girls around your daughter's age. When she plays well with another child, speak to the child's parent and ask about setting up a play date. Find a mutual interest art, dolls, rollerblading and encourage them in that direction. Check out homeschooling support groups in your area. Try different field trips or group activities for kids her age. Be prepared to drive. I network with other homeschoolers within a 45-mile radius. By meeting many families, your chances of finding appropriate playmates increase.
This phase will pass as your daughter matures and is accepted into a wider age-range group. In the meantime, don't give up trying to bring new friends into her life, but don't emphasize their absence either. Focus on all her special qualities, and enjoy your time together.