Breast milk and formula milk

i was apart from bb for 3 days due to him hvg high fever and jaundice. he had to stay at kkh w my husband as the covid situation allows only 1 companion. i did not read much abt bf so i did not pump to regulate milk supply. i regretted it till this day. im still trying to find alternatives to regulate my bm but i still give my bb formula especially when i feel like its not enough for him. :)