Breastfeeding

My baby is 7 days old & I'm new to breastfeeding. My baby doesnt seem to want to nurse for a long time, she only nurses for 2 mins & falls asleep & shes wanting to nurse every hr sometimes less than that. When she gets latched it seems like shes getting a lot bc it sounds like shes taking big gulps & has been unlatching after a min. & if I put her back on the same side she only goes for another minute. The couple of times she was latched for a long time she had a very forceful burp that seemed like it hurt for her to get out. I did pump for maybe a day bc I didnt think she was getting enough & was just going to do that instead of nursing but I missed it so I tried going back to it after doing that. Im just worried shes not getting enough bc at 6 days she was only 5 lbs 14 oz & st hospital was born 6 lbs 1 oz. Dr also said she had a slight tongue tie. Should I consult a lactation consultant? Am I doing something wrong? Any tips or tricks you guys can send me is appreciated 🙂