My son is 14wks he drinks 9oz of the hungrier bbs milk. can i give him rusks?

Hes been on the 9oz of hungrier baby milk for 4 weeks, he sleeps through the night but in the day hes going less and less time between feeds, now i feed him, change him and put him to sleep he sleeps 4 20 mins and is hungry again, uve tried water to see if he thirsty but thats not it. i cant cope its driving me nuts!! HV said not to give him rusks because at 14weeks his body cant cope. but I was weaned at 10wks and im fine!! I feel he needs that bit more but im scared ill get into trouble or it may harm him. should i just give him say a 1/4 a rusk a day or somin?