A supply line would definitely give her the reward for suckling at the breast. Being topless at home can help too. I used a Medela SNS with my DD due to diagnosed low supply and she had formula in the SNS and got breastmilk from me at the same time. As Barb said, its the stimulation that builds supply and your DD would be better at stimulating your supply that a pump- I did both for a while.
I also took motilium- 9 a day at one point under the guidance of my GP and awesome LC- Leonie Maybury from
Eastern Lactation Consultants in Melbourne.
Good on you for being willing to put in the work to relactate.