Hi from a fellow Med student
I can relate to what you said. I thought about seeing a therapist for about 4 years (even making appointments and not going) before I finally did. I think my symptoms started when I was about 14/15 but my cultural and family environment didn't encourage me to go see a physician (which meant being crazy to them), so I just kept internalizing everything. I didn't even know BPD existed, and when I was 17, I started med school and began thinking I was bipolar type II, because that's what seemed to fit the most (even though some symptoms didn't really).
I was scared as hell to go see a doctor, I didn't want to be labeled as mentally ill or something, I saw mentally ill people during my internships at hospitals and it freaked me out to think I was like that. I don't know about you, since you're a first year, but the further you go in med studies the more you think you can self diagnose/medicate and the less you wanna go see someone...
So anyway, I made appointments, then my mood would swing to fear/shame/guilt/whatever and I'd cancel them, but somehow I WANTED validation, deep inside I really needed a diagnosis.
This is how far I went to get one without going to a doctor... Don't judge me.
Last year (I was a 3rd year med student), we had this assignment where we had to write a paper about a patient with a chronic disease we met during our internships. Could be diabetes, MS, or a mental illness. The professor grading us was a well known psychiatrist in my town. SO, naturally, I decided it would be a good opportunity to write about..well.. myself. I still thought I was bipolar at the time (and I do have some bipolar tendencies) and I described everything I felt/had done in 3 pages. I thought : well if I'm wrong, he'll think that I've invented the whole thing and call me out on it, no one will know it was about myself, they'll just think I cheated. But I had a great mark, and he told me I had successfully captured what mental illness felt like, he also asked me if the patient had BPD. I didn't know what it was (I had heard it before but never looked into it). When I did look it up, suddenly everything made sense and I fit all the criteria. I read testimonies of BPD people, and I swear it could have been me writing them.
Now I was finally convinced that was the right diagnosis, and it kind of lifted up some of the weight, I felt less confused about what was going on in my head and I could at last put a name on it. I thought it would be enough, that I could manage. It was still a secret (I told no one), I was still ashamed... I read that no medication had been proven to be an efficient treatment for BPD yet. I thought: no need to see a pro, he'll just prescribe useless treatments that'll turn me into an apathetic zombie.
Then, about 6 months ago, I almost killed myself.
I've been seeing a therapist for 3 months now, he's a good listener, and even though I'm still not a 100% comfortable with him, he helps me exteriorize everything and put some sense into all of it.
Living with BPD and not being able to talk about it to anyone is a bad idea in my opinion. Nothing good can come out of internalizing it all. Therapy is essentially a work on yourself but a little guidance from a professional can't hurt

.
Sometimes, someone who doesn't judge, whose goal is to listen and help you make sense of things can make a big difference.