its so confusing

During the intial episodes zoya said to dilshad that its her mother's death anniversary so according to the story 17yrs before when zainab died it was najmas b'day but they never mentioned anything about it & according to the narration of the story najma must be 18yrs but they have shown that she had just completed ba before her marriage so she should be atleast around 20yrs & also in the story they said that when rashid came with ayaan he was only 1yr old & dilshad was full term pregnant with najma so if najma is 20yr old then ayaan will be 21yrs right?

i think they said
3 years old ayaan and 7 years old asad
when rashid came back

What najma said to zoya was ayaan bhaijaan came with abbu when he was only 1 or 2yr old & also dilshad once mentioned asad was only 8yr old when rashid left them & ayaan was only 3yr old at that time so if we see accordingly ayaan must be 21yr old now since humiera metioned that it was ayaans bday just b4 eid & she went missing at that time & as far as I understood ayaan & zoya are of same age 17yrs b4 she was only 3yr old & now today as they r showing it as zoya bday she also should be 21yr I think they made a mistake with najma age