premature baby feeding

hey girls, my son was born premature at 34 weeks and is currently 4 weeks old and I am really struggling with expressing. He struggled to breastfeed in the hospital so I have been expressing breast milk and bottle feeding him since he was born and I’m considering giving up as I cannot cope emotionally and physically with expressing constantly, especially as he still struggles with full feeds on the breast (although he has improved). He is currently combi fed as my supply decreased when leaving hospital but considering switching him exclusively to formula. I honestly feel so guilty about considering it as I have so much anxiety about his health as a preemie and it has been drilled into me that “breast is best”. Has anyone been in a similar position before?