hye..my wife already 30 weeks n twins mma..but our bby still smal..have any suggest to get bby bigger?

Anak sye baby prem.. lahir 1.8kg on 31weeks.. bf until 2months & fm i try isomil.. yeyy baby i naik berat smp overweight.. alhamdulillah.. tp tulah, ikot keserasian baby jgk kan