Frustrated - hearing issues (blood pressure, heartrate)

I have slight hearing loss in one ear, supposedly just very low tones. I've been practicing heartrate and blood pressure on everyone and most of the time I just can't hear it. I've only been able to hear blood pressure on one person and heart tones on three. Unfortunately, my lab partner has been none of those. I have a meeting with my professor on Tuesday to practice skill testing (soonest appointment I could get). I am just so scared. I don't know what to do. I've tried two different stethoscopes (Littmann and whatever the bookstore was selling). We need to pass 2 out of 3 tests on blood pressure before the end of this month. I couldn't sleep last night at all. The only thing I could think of was my career in nursing being over before it even really started.