your scan findings are normal and are according to your gestational age
as pregancy progresses the size of the uterus
increases leading to dragging of ligaments supporting it that may be the cause for your pain in lower abdomen and back.
you avoid standing for prolonged periods
take help of physiotherapist to reduce the pain,
take rest for 2 hours in day time and 8 hours for night time,
sleep preferably in left lateral position,
take nutritious diet and good hydration.
as you had normal delivery for the first time this time also you may have,
but if the baby is big and any associated complected problems like decreased liquor, uterine inertia
etc are present then the mode of delivery may change.