firstly, congrats on Olivia coming home you must be chuffed to bits
Stick with the slow flow teats for another few feeds and see how she goes, may just take her a little longer to get used to them and having to work a bit harder to get the milk but she will soon get the hang of it, after a while you will see her either take to it brilliantly or she will make a huge demanding fuss in which case try the next teat up and see how she goes.
As for the choking, speaking from personal experience here it always seems a lot worse than it actually is (no offense) its all part of getting this tiny baby home with no alarms and no one trained looking over your shoulder, will take you a few days but the confidence will come, I promise.
In the meantime, if she chokes just gently raise her up or place her on your shoulder and rub or pat her back, I remember with Matthew it was as if he forgot to breathe afterwards, gently rubbing her cheek will soon get her going again it is very scary the first few times but as her body matures these episodes will decrease.
Remember, the NICU are more than happy to help offer advice - day and night for the first month or so, any concerns at all call them up. Id also call the HV service again and fill them in on Olivia as a full week is far too long for you to go unsupported, id say 2-3 days max as Olivia will need weighed to ensure she is gaining weight, I would specify that another HV from any GP surgery pops in even if its just once for an initial chat and weigh. (I was in a diff practice from Matthew to start with and his HV was unavaialble also, I explained our situation and they organised a HV from my practise to visit and weigh him and she liased with his current HV to pass on info - hope that makes sense
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I hope you try and relax tonight as I know no sleep will happen you'll lie awake staring at your gorgeous girl and every peep you'll be up checking her.
Welcome home Olivia xxx