You started PEP well within the 72 hour window period, so that is very good.
I could give you a lot of information about PEP, but THE most important thing for you to do immediately is get in touch with an HIV Specialist who will follow you through your 28 day treatment period and advise you regarding the appropriate post- PEP testing schedule. I am surprised the ER docs did not recommend a specialist for you, as this is standard procedure. Call the ER as soon as you possibly can and ask for a referral. If, for some odd reason, they don't know of anyone, contact your own doctor. Please make these calls tomorrow!
RW