Thanks for the query..
There are few more details needed before answering..
Are you still feeding your baby?
Are you using any methods of contraception
to postpone pregnancy?
Now, there can be hormonal
imbalances after delivery which cause irregular periods?
Again, are your periods just delayed or associated with excessive bleeding?
You can get an ultrasound
of abdomen and pelvis done to rule of any condition like fibroid
It could just be a hormonal imbalance for which your gynecologist can prescribe some pills for regularization of periods.
You ht and wt seem to be in normal range..
Hope I helped you..