Baby feeds for only 10 mins on one breast

My little one is 2.5 weeks old and will only feed on one breast for 10 mins at a time. She feeds every 2-3hrs. She often falls asleep while feeding and is not interested in drinking more when I try to wake her.

She is past her birth weight and has a lot of wet diapers but usually only 1-2 poos a day, she’s also gone 24hrs without a poo in her second week.

When I’ve used the Haakaa to collect let down, I seem to get 20-30ml of milk from one breast, so I’m assuming that is how much baby is getting per feed.

How do I know if there is Hindmilk in what she is drinking? Or just foremilk?

I wouldn’t be so worried if she was pooing more regularly but she also seems to be very gassy after every feed / grunting / struggling to settle as if she needs to poo but can’t.

Any advice is appreciated :)