Talk to Gynecologist on Postpartum Contraception

I am 2 months postpartum and exclusively breastfeeding my baby and need reliable oral contraception. I have been prescribed exulton (0.5 mg lynestrenol) but I cannot find it so primolut n was prescribed as an alternative 5 mg BD. I have the following questions: 1) I can I take lynesterol 5 mg instead of 0.5 mg and if yes what is the daily dose? 2) is primolut n safe for breastfeeding I don't want to discontinue breastfeeding my baby. is it a reliable contraceptive? what should be the daily dose? 3) if not then what are the alternative options for me in oral contraception?