@niinii
(a) when did you enter the USA with F-1 ? When did your wife and child enter with F-2?
(b) The form 8843 is ONLY for those students whom are confirming that they are still exempt ( i.e. exempt from counting days present for SPT purposes ).
(c) If you have passed the SPT ( Substantial Presence Test ) then you are a Resident for Tax purposes --- you file a return on form 1040 ( not 1040-NR ) and are taxed on your world income.
(d) since your spouse and child are on a dependent visa ( F-2), their tax status is same as yours i.e. if you are a Resident for Tax Purposes , they are also Residents.
(e) If you are a resident, then you are free to file a Married Filing Joint and include your child as a dependent.
(f) Note that for filing jointly, each must have a Tax ID --TIN ( SSN / ITIN )
(g) Which country are you from ? How about your wife ?
Is there more I can do for you ?