Most of the time i have periods exactly as predicted by my period calculator. other days i'm 1-3 days earlier or late. cycles average 26-29 days. are these irregular cycles?

No. These are minor variations on a normal pattern. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines