Low weight of baby at 30 weeks

I visited my gynac yesterday and my babies weight is approx 1.2 kg currently which falls just below low weight criteria.

I am not eating enough just normal roti sabzi in lunch and rice with sabzi for dinner.

Have roti With chai for breakfast.

Drinking one glass milk at night which I also miss occasionally.

Not taking any other thing than this .

On bedrest due to cercalage and my mother is not be able to cook more than this.

I am worried for my baby .

What to do now?