I am gaining to much weight and have irregular periods . what is causing this.

Hormonal changes : Can include under- or over active thyroid, changes in insulin/blood sugar regulation, changes in estrogen, progesterone or testosterone or the the stress hormones, particularly cortisol and DHEA. All of these can affect your cycle and your weight. See a doctor to have your hormones evaluated, including thyroid and insulin. Premenopause can also begin as early as 35.

Best get checked: It's hard to know, need to see aDoctor and have all your hormones checked and discuss life style.