Certain creams or medicines could be harmful for you, but a dermatologist will advise accordingly.
Since you are breastfeeding, you can use topical retinoids, which are anti-inflammatory medicines that unclog pores.
Benzoyl peroxide is reliable as well.
These topical acne medications serve as antimicrobials and help unclog pores.
But a dermatologist would give better guidance and take more things into consideration, so approach them - Dermatologists in India.