Hi..You are a young lady who is overweight and has delayed periods.It could be
(1) polycystic ovarian syndrome.
(2)
Thyroid disease.
You need to get a gynaecologist opinion and have a ultrasound scan abdomen to assess endometrial thickness and ovaries thyroid profile,
prolactin assay,
FSH,
LH assay .
But as a primary thing from your aspect you need to reduce your weight.
Hope this helps