So would I be right in saying that now you want to exclusively formula feed and not breastfeed or express milk at all?
I'm all for mothers deciding whats best for their families as long as it is an
informed decision, especially with a preemie.
Not breastfeeding does come with its risks, and with a baby as young as yours who was premature I am inclined to encourage you to breast feed your baby to give him/her the optimum health they can have. As well as for your own health.
Please make yourself aware of the risks of not breastfeeding for you and your baby before making your decision. Here's a useful link that will help you make an informed decision. https://www.infactcanada.ca/RisksofFormulaFeeding.pdf
Introducing 1 formula feed every 3 days would be a safe way to go about it reducing the likelihood of engorgement or mastitis.
So you'd be expressing all feeds except 1 formula feed for days 1-3
The same again only 2 formula feeds for days 4-6
Then days 7-9 3 formula feeds.
And so forth till your on all formula feeds and no expressing. It will be uncomfortable for a while, you can take paracetamol if you need to. You should also wear breast pads as you will probably leak for a few weeks until the milk dries up completely. Some people will dry up in a matter of days since they last expressed or breastfed, others can take week or months. It just depends on the person.
You could just go cold turkey if you wanted and not express at all anymore, but you are at risk of getting all kinds of infections and illnesses this way and it is REALLY not advised, especially with such a young baby to care for it's going to be a lot harder if you are ill too.
If you run into any difficulties please don't be afraid to ask us here. Best of luck whatever you decide