I feel your pain, and I still have twinges of regret and sadness.
At the same time, I know that STOPPING trying to nurse my babies was the best thing I did as their mom . I had a severely low supply andwas so focused on bf and pumping and meds and lc's (even saw a DR who specializes in bf medicine, oneof onyl 50 int he U.S.) that I was not bonding with my babies. I was getting frustrated that my ds was impatient and hungry, and my dd was too tired to latch for long. I hated the pump, I hated my breasts and my body, I really hated formula and bottles. Every feeding was stressful.
When I finally gave in ater 4 months with ds and 5.5 months with dd, there was only ONE person who said it was ok: my best friend who had bf both her children for over a year. She had had major latch issues with her first child and knew how hard it is, and also the toll it was taking on me. I needed that ok to give myself permission to say "I can't do it, but my babies will be ok."

the most important thing you can do for your baby is to be her mom and meet her needs, however you are able to.
Christine