hmmm in my opinion..
for the roasted pig, u will need 2 brothere to help u with it. at least.
for yourself thruout the day, u will need 1 jiemei whom u can entrust all your belongings to, like ur makeup pouch, mobile phones etc. you will also need someone to help u change ur gowns in the day and during banquet. it can be the same person for these 2 roles.
during tea ceremony, you will also need someone to safekeep the angbaos for both sides. it can be a jiemei and a brother. but if u and htb are ok to have just 1 helper to oversee this part, thats fine too.
you will also need ppl to help u at recep. that will be flexi and its up to u. but usually better to have at least 1 frm ur relatives side and 1 from ur friends pool for both the groom and bride side. u will also need the brothers to help ard the logistics like getting ppl ready for table shoots, someone to do AV if there's a need, and more imptly, assign someone who is the overall contact pt.
so all in all, you'll need at least 2 brothers and 2 jiemeis for the whole day should u these 4 ppl be "usable" for entire day's duties.
i donhave gatecrashing too and ill be doing dinner banquet. for me and for now (since my wedding is only in dec 2015 and i havent really get down to confirming the ppl), i will be having 2 bros n 2 jiemeis for the day. my recep ppl for bride's side will be entirely diff group of ppl.
so all in all.. i guess its all up to u
list down the rundown of the whole day and see which are the areas u think u need help in.. hope it helps!