Hi vel, what pump are you using?? for me, max speed doesnt give me faster letdown so i set around medium speed.
Sterilizing wise, i sterilize twice a day, and i pump around 6 -7 times a day. I do pump more than 30 mins if my breast are not empty provided my nipples still can take the suction.
No problem to combine milk from both breast into 1 bottle.