GDM underweight

Anyone here yang preggy underweight/kurus tapi ada gdm. How you guys control makan & gula? My weight is around 40-42kg, idk if i can handle this or not. Down 😔 harini khamis, isnin depan dah kena start bsp. So any tips tak diet yang sesuai. Saya dah takut2 nak makan minum pape ni. First time nak try diet sebab saya memang kurus so tak pernah control pape 😔 FBS: 3.9 2HPP: 9.4