Pumping

So I'm trying to pump breastmilk for my baby cause I'll be going out of town just for two nights maybe one if things don't go well & I freak out. (It is my first time leaving my baby since he's been born) he's almost 6 months. I've been EBF since he was born. Anyways, my problem is I can't get ANY breastmilk at all out of my

Boobs & I don't know what to do...

like I only got a couple drops after pumping for like 10 minutes.

Any ideas ???? Would it bad if he drank formula while I was gone? Would he not take the boob by the time I come back? Please help! Thank you!