Good afternoon Nancy!
I recommend you to be more proactive and brave to find good mentors. I would like to share my story with you.
When I was in university in South Korea, I was also eagerly looking for my career mentor. Thus, I participated lots of career events to meet people who could be my mentors. One day, VP of Facebook Korea visited my university for alumni event. He told us about how he overcame his numerous failures and how he made the decision in his important life points. His speech was super impressive for me and I wanted to meet him in person to get some advice for my career and life. However, he was super busy person and left the university right after the speech.
Can you guess how I meet him in person at that situation? I searched his Facebook account (because he worked at "Facebook", I was sure that he may use his account a lot) and sent my sincere message to ask for short interview time. As you can expect, he sent me the reply but asked me to visit his office WITHOUT LOCATION (?). At that time, Facebook just set up the Korean office separately from Asian office and there was no official address information in the website. Thus, he wanted to test me whether or not I really wanted to meet him although I had to spend extra time to search and find its new office.
Well, it was hard to find the address but I finally found that address in Singapore article! (I might spend full day to search it.) At the end, I met him in person at his office and got various advice about my career and life. Since then, I occasionally communicated with him to get some advice and he always responded to my message.
If you really want to meet the mentor in your field, as I mentioned above, I recommend you to be more proactive and brave. You could visit college career events. Or, you could contact your alumni who work at companies you are interested in. They could ignore your message as they are busy people. However, there is a possibility for you to meet someone who is open to help students like you. Just try it first and see what miracle happens!