Weak ovulation

Sooo I found out today that my hCG levels are really low and show that I had a weak ovulation this month. My doctor said that since my ovulation is so late in my cycle (day 21ish) that she was worried about that so she had a blood test done. Sooo now I've been prescribed clomid to try this next cycle. Has anyone else been told this or been told they have "weak" ovulation?