HIU,
I understand your concern.
Pregnancy with overweight can be due to many causes like -
gestational diabetes,
hypothyroidism, urinary infection / heart problem with swelling on feet/ Cushings syndrome-/ family tendency.
You need to consult a physicisn/
endocrinologist for specific investigations ,diagnosis, treatment of the condition. Simply eating less is not the answer ,finding the basic cause & it's treatment will stop the weight gain.
Excessive weight in pregnancy brings risks of Urine infection,
high blood pressure, complications during child birth, LSCS delivery,thombo embolic problems, infection.
Baby carries possibility over weight, congenital abnormalities ( detected by USG),
premature birth.
You need to be in frequent check up by expert gynecologist,TRy to note appearance of swelling on feet/ rise in BP/ urinary problems/ fetal movements.
With expert advise & close observation & care would lead out of these difficult days Don't worry.
Thanks.