Aww mama, jangan risau sangat, banyak baby macam ni, especially kalau mixed feeding like yours. Tapi sebab baby baru 3+ bulan dan intake dia macam kurang, better check dengan doc or paediatrician kecil to rule out anything, maybe latch issue, reflux, or dia just prefer susu badan kat certain times (some babies do that!). A few of my mum friends had babies yang minum sikit-sikit tapi sebenarnya okay lang, tapi memang kena monitor weight gain and wet nappies to make sure dia getting enough. Hang in there, doctor boleh guide you better on whether kena top up lebih or if it's just his pattern.