Expressing milk

Hi mummies, how was your breastfeeding journey? I was overwhelmed as my milk was not ready when my baby was born so had to intro formula first. Only after the 5 days, my milk appeared but when I tried to pump my milk out but only a little came out. It made me stressed. There was alot of milk spilling too and but i can't seem to express all the milk out, only 30ml each time. Is this normal? Will my milk flow improved overtime?