Make sure you’re bringing the baby to the breast and not the breast to the baby. So sit in a chair that’s comfortable and have extra pillows to support the baby if she needs to be brought to a higher position where you can maintain your posture
Honestly the best breastfeeding support pillow I’ve used is actually a giant squishmellow of a Pokémon named bellibolt she sits into it just perfectly for a food football hold and it gives my elbow the perfect amount of resistance for other positions
I have multiple small long pillows to get baby to a comfortable height & angle. Reclining on the sofa works well for us.
My brest friend is the one that I liked the most. It goes behind you and has the spot for baby plus clips like a belt so it doesn't slide down. I will say they are a bit pricey though so try to find one second hand
Also highly recommend attending breastfeeding groups like Leche League or NCT or whatever is available in your local area. So helpful for tips/suggestions/encouragement 💕
I learned to have a long pillow and have it behind me, not in front. That way the shoulders are more relaxed