Need advice, please! A little bit urgent

Twinklestar7

I SAH and EBF. My baby is four months old.  I have never used the pump or the bottle up until yesterday.  At first I tried feeding her formula, to see if she will take it, but she absolutely refuses it.   So I started pumping today for the first time, and I am shocked that three times I tried to pump for 15 minutes each, I got only 3 ounces in total ( about one ounce each pumping session.) This was after I finished breast feeding her, then I went off to go pump.  Does this mean my supply is low?  Or just she drank most of what I had before I pumped? She never acts hungry and if she is, she is good at letting me know.  So I dont know what to think about my supply- is my pumping method wrong? I have a Medela PISA, and first time I kept it at at a 2, then upped it a 3 the second time, then a 4 the third time.   I dont plan on continuing pumping but, tomorrow I have to go out, and my husband will be staying at home alone for the first time with her. He needs to feed her for the 5-6 hours I will be gone and she wont take formula.  Please advise.  Thank you.