Supplementing to build up milk supply

Since my baby girl was born she was never able to latch properly so I took on the challenge of exclusively pumping, its great but my milk supply is low and I am returning to work soon. I want to give her only breast milk at daycare so I wanted to supplement for the next week to build my supply. Is it okay to do that? Does anyone know what formula is best? What to look out for in formula? I just want my baby girl to be safe I am not the biggest fan of formula I was always so strongly breast milk only... I didn't think it would come to this