Will my menstrual cycle be regular when I'm breastfeeding?

Probably not. Suckling stimulates maternal release of the pituitary hormone prolactin; high levels of prolactin (due to any cause) are usually associated with infrequent or absent periods. What you actually ecounter is individual though, and may be affected by many factors such as frequency, duration, and amount of nursing you do.
Menstrual cycle. Usually at the beginning of breast feeding the menstrual cycle is absent or irregular, but as the feeding continues over months the cycle becomes more regular.