Hi there, I have understood your concern and I will suggest you the best possible treatment options.
First of all do not panic.
If you have history of regular cycles, then as per LMP of December 29, your expected due date will be October 5.
It's 40 weeks from your date of last menstrual period.
You can relay on dating USG scan that must have been done around 6 to 8 weeks of
pregnancy.
If USG is done at 18 weeks and shows corresponding babysize and satisfactory interval growth from last USG scan, then you need not worry about growth lag.
Please opt for a healthy diet and regular exercise regimen.
Start on
Folic acid and vitamin B 12 supplements regularly, this helps to prevent various
complications during pregnancy and childbirth.
After 14 weeks, add iron, calcium and
protein supplements to your daily routine.
Think positive. Meditate regularly.
May God bless you with a bundle of Joy.
I hope this answer helps you.
Thanks.
Dr. Purushottam Neurgaonkar