What you are doing is feeding on demand, which is correct. Babies around this age drinks every 2 hours. As they get bigger and their tummies can hold more milk they usually eat every 3 to 4 hours. Hence you do not need to wake her up. You can look for these signs as an indication if your baby hungry: *moving their heads from side to side opening their mouths *sticking out their tongues *placing their hands, fingers, and fists to their mouths *puckering their lips as if to suck nuzzling again their mothers' breasts showing the rooting reflex (when a baby moves its mouth in the direction of something that's stroking or touching its cheek) *crying
One way to know if your breastfed baby has had enough is to check her diaper output. At 7wo, she should be having 7-8 wet/dirty diapers in 24h. One wet diaper is about 45ml of liquid, you can try it out on a new diaper to see how heavy it should be. If your bub has got healthy diaper output, you need not worry about the duration of her suckling at night etc. Some babies just want to soothe themselves back to sleep in the middle of the night, not exactly waking up for milk.
Studies have shown that breastfed babies between 1 to 6 months take in an average of 25 oz or 750 ml per day. As long as your baby gets that amount of milk thereabouts, there is no need to wake baby up - it should be okay :) if she's still hungry, she'll let you know (eg crying or nuzzling at your breasts)
Since she has already wake up every two hourly, there is no need to wake her up for more. 7 weeks old is still not capable to consume so much, 5-10 mins is quite sufficient to fill up her tiny tummy :)