Breastfeeding dilemma

When my baby was 2 mths old my breastmilk was drying and only manage to pump for 3 to 4 feedings a day. It was due to stress and insufficient sleep and rest causing my milk supply to drop. My girl has been formula fed ever since and now she is at 4mths + I am feeling depressed and guilty still for not able to provide her breastmilk. Any of mummies here facing same issue? Can anyone please share if your children grow up well even with formula milk? My first baby hence the anxiety.