Delayed Breastfeeding

My baby girl just turned 3 weeks. Unfortunately I have been unable to breastfeed her because of complications in the hospital and Meds they gave me. I was told to wait 3 weeks. I'm going to try tomorrow and I'm so nervous! I've been pumping but even if she does latch (I'm prepared to exclusively pump if she doesn't) I've only been able to produce 2-3 ounces each session. She is drinking 3 ounces of formula right now. Anyways, has anyone had to wait to breastfeed and has some advice for me? Thanks!