Alhamdulillah, syukur you dah sihat semula, please don't be too hard on yourself, sebab bila badan kita sakit dan tak makan dengan cukup, supply drop memang sangat common. The most important thing now is to nurse or pump more frequently to signal your body to produce more, because milk supply really does depend on how often the breast is being emptied. Do also make sure you are drinking plenty of water and eating nourishing foods like oats, kurma, and nuts, I've heard that raw papaya soup and dates water are quite popular among mummies to help sustain flow, so it may be worth trying those too. Rest whenever you possibly can as well, because your body is still recovering and stress really does affect letdown. That said, since your little one is already supplementing with formula, it might be wise to check in with a lactation consultant or your doctor just to get proper guidance tailored to your situation, wishing you all the best, mummy, you're doing wonderfully!