Every 2 hours or demand feeding i.e feeding when the child starts feeling hungry and cries is the correct method. Pee frequency is also good. The duration of feed is as per the child. But generally 15-20 mins suggest that baby has taken adequate feed.

Yes every 2-3 hrs you have to continue feeding the baby. At this stage you have to pick up the cues baby is giving you showing that baby is hungry for eg. crying, sucking fingers vigorously, got up from sleep crying etc. Make sure baby is passing urine >6 times a day and gaining weight. Finish feeding in one breast completely before switching to the other breast followed by a good burp. Usually each session requires 15-20 minutes minimum.

Didn't mention the birth weight and present weight. Breastfeeding should be now on demand, especially have crossed 3.5kg of weight. Sometimes it may be once in 4 hours also and that is also normal. Child has soothing effect when does a sucking movement, especially in pain (like due to colic) so need not to feed all the time. Weight check up once a month to know whether you are on the right track.

Newborn babies should breastfeed 8–12 times per day for 2-3 month. Breast milk is easily digested, so newborns are hungry often. Frequent feedings helps stimulate your milk production during the first few weeks. By the time your baby is 2-3 months old, he or she probably will nurse 7–9 times a day. In the first few weeks of life, breastfeeding should be "on demand" (when your baby is hungry), which is about every 1-1/2 to 3 hours. As newborns get older, they'll nurse less often, and may have a more predictable schedule. Some might feed every 90 minutes, whereas others might go 2–3 hours between feedings. Newborns should not go more than about 4 hours without feeding, even overnight.