Overfeeding baby

Have any of you had a 3 week old eating 5+ ounces at a time? I'm worried I'm going to overfeed her but she is ALWAYS hungry! She will eat 4 ounces and be hungry again within 30 to 45 mins. I try doing other things with her (like the 5 s's) but she is constantly trying to eat her hands and rooting and shes not all that interested in a pacifier. Shes gained about 1.5 to 2 pounds from her birthweight in 3 weeks, sleeps great, and barely spits up. Anyone else have a super hungry baby? Is it okay to feed her when shes hungry or am I going to cause problems for her?