I would keep your chin up. As Goro said, you have to operate under the assumption you are rejected until you receive an acceptance. It took me a few cycles to get into school and the first round, I did not have this mindset. It definitely led to some serious heartbreak, and definitely led to a little soul searching to see if I wanted to try again or change direction. I am glad I didn't change paths looking back, but I also know it was a struggle. To think of it as rejected until accepted almost helped me grow and continue to improve myself and my application for future cycles.
I also had a sense of slight guilt (not really sure of a better word for that feeling) because my parents financially supported me to be able to attend interviews, and only a handful were within driving distance. It sucked to come home for Sunday dinner and report that I had not yet been accepted, but I was fortunate that they were still supportive and would sometimes help evaluate potential week points in my application. It also made it that much sweeter when I got my first acceptance. I actually started crying when I opened my email and again when I got off work and home to tell them.
The best advice I can give you is be yourself whenever you are at interviews, but also be critical about your application. Be able to look at your application with a critical, objective eye and say to yourself "what can I do to improve this?". It is harder to do this for your interview because everyone has a subjective and/or hypercritical view of their performance within the interview day. For these, practice interviews, practice answering questions you know you will likely have and practice answering questions/having conversations without sounding canned, forced or rehearsed. It feels uncomfortable to go through this, but it definitely helps. I had one person record me during the mock interview I did and I was able to watch myself back (much like athletes watching back games to see what went well and what can be improved on). That feels really awkward, but gave a lot of information.
Chin up. Use this opportunity to grow yourself. It may take multiple cycles, but if this is what you want, then you will find a way to make it happen. Be willing to make changes and grow. Be willing to get uncomfortable and make changes. And if your parents are willing to support you to get to your dream, then you have no reason to be guilty. They want to see you succeed. Every interview and every application is a risk that you will or won't be accepted, but you have to do the best you can. Be the best you and don't give up. The biggest thank you to them (or at least it was to my parents) was getting the acceptance email. And in a few years, it will be walking across the stage, graduating from medical school.
