The nice thing about school is that you can try different things and subjects and if you plan on continuing to grad school you really have some time to try different things out. It sounds like you want to make a decision weather to be more mechanical or electrical in your focus. My question would be, what do you like about biomed and bioengineering? When you imagine working in these fields, what do you think of? Is there a specific area you are interested in? For example, let's say you want to engineer pacemakers. Go online and look at journal papers on how pacemakers work. Then find institutions that make pacemakers and look at their job descriptions. If you do these two things, you will:
1. Figure out if pacemakers are really of interest to you
2. If they are, through job descriptions you will get a better idea of what the engineers who make pacemakers need to know. This will in turn guide you through the classes you need to take to get there.
Apply these steps to the topic you think you are interested in and try a few different things. As far as classes being hard, engineering is hard :) but what makes it great is that you figure things out and you solve a problem. Engineering classes are a right of passage to solving problems and if you keep trying, eventually you get good at it.