after immediate miscarriage
there is chances of irregularity of periods.
but by 6.5 to 7 weeks the fetal pole even heart beat of the fetus can be seen usually,
and the size of the gestational sac
should be around 1.5 to 2.5 cms.
that too as you had heavy bleeding,
the possible chances are,
- blighted ovum: in which gestational sac without embryo will be present.
so you better take second opinion
with another gynecologist and proceed according to that.