My little one is 4 weeks old and I've exclusively breastfed all but 3 feeds.

My issues are:

1) My let down seems to have gotten a lot faster in each breast and the first few sucks are fruitless but after that my daughter gets flooded coughs, chokes, takes air then cries. When I pump, it takes a good 10 minutes of solid pumping before the flow is manageable

2) She is only feeding from one breast each 2-3 hours during the day and is only on for 10 minutes. This can't be enough since I pump only 60mls in 10 minutes. She just isn't interested in taking the other side, so each breast gets stimulated every 6 or so hours, however my supply is abundant and I'm pumping 120mls once or twice per day

3) My daughter has gotten to a point where she cries and throws up after each breastfeed, so I've tried her on Nan HA1 3 times in the last 2 weeks and she's been perfect and took 90 mls. I then tried her on the EBM via bottle, throws up (not as much as when on the breast) so I'm comfortable it's not my milk

4) I really want to give her 1 bottle only of formula per day, but am really concerned about her bowel movements. She hasn't had once since Sunday and while I understand breastfed bubs might not go everyday, 4 weeks seems young to stop having them plus considering she's had 1 bottle of formula on Monday, I would have thought we'd see something. I don't think it's the formula since it's designed for babies who have allergy and digestive issues - it's partially broken down

My questions are:

1) In terms of the speed of my let down, I changed positions and the only thing that achieved was bub sucking in air, what is the BEST position to minimize air ingestion and slow that flow? Also, since it's sped up, will it slow down in time?

2) Do I need to keep pumping with her frequency of feeding? I've only done it in these last weeks to ensure her time between feeds doesn't affect my supply, she is feeding approx. 6-8 times per day and sleeping approx 8 hours overnight

3) I suspect the reflux my daughter has is because of the fast letdown and the choking. I can't see how else it is there for BF's but not bottle feeds. It's so bad the poor bugger will still throw up 2 hours after the feed....will a nipple shield help slow the flow?

4) Is the fact she hasn't had a bowel movement in 5 days a concern? Bare in mind she has had 1 bottle of formula in those 5 days, so if she is no longer going to go once a day because she's breastfed, shouldn't she at least be doing something with occasional formula? I should say that in the days leading up to Sunday she was only doing small bits while passing wind - so not sure if her movements were slowing down naturally anyway - I guess I'm concerned because since the one bottle she hasn't gone and I would have thought she should have with that (remembering it's NAN HA - highly unlikely to cause constipation - or that's according to my Dr would love to know if anyone has had constipation as an issue with this formula)

5) I drink a lot of water and vitamins when I remember, but my diet is shocking. I never really eat throughout the day - only dinner so I am concerned that the quality of my milk is not the best (hence why I would like bub to have the 1 bottle of formula per day so she's at least getting something stable)

A huge THANK YOU in advance for any help with the above, I really wanted to BF long term with Cary - but I never anticipated it would be this hard