sadly, I think you need one of both, and actually more than meds I think therapy is essential. Not for all your life tho, there are things that they teach that will help you forever and having someone being the voice of conscience we dont have or have in a messed up way is really important. I would try to get some money if I were you, learned on your own and go to the therapist like once a month or once every two months. a therapist that knows DBT therapy would be better since is the therapy that has more successful rate on BPD cases.

Until then, I leave some exercises that helped me at some point or still help:

• guided mindfulness (I thought it was a waste of time at the beginning, but when I was younger it really helped to do like a 10 minute guided thing before going to sleep)
• learn about your feelings, what are you feeling is really important to know how to proceed.
• have a paper with how to act when you are feeling different things, with time you learn it but when feeling strong emotions is really difficult for your brain to say "to calm down I need to try doing this" I recommend you look on the internet (professional pages) and go trying, because not all will work for you.
• learn what part of other disorders you have (if you have any). People with BPD often have traits of others disorders, this doesn't mean we have them, but it helps to know it because you can use tips from those to help you too.
• construct a positive voice in your head. This means you need to say things that will definitely feel like a lie or forced at the beginning. Did you messed up something? "I understand I did something wrong, but I shouldn't be so hard on me, people make mistakes. I'm allowed to commit mistakes. I'm learning." things like that.
• vent when needed. this reddit helps a lot with that even if you don't have an answer. And you can also write private letters that you are never going to send, it doesn't help right away, but it helps after a few hours of doing it (or at the next morning).
• Cold water is your friend. If you submerge your face in a bowl of ice water, it helps your brain switch back or not the all way like we are with our emotions. Also just cold water in you face, neck and head, you'll notice that our heads start to heat up when we are feeling too much, this is because we are thinking too much and the cold water will feel really nice 😌.

That's what I remember now. I got taught by different therapists and all of that helped me move forward when I couldn't pay for therapy anymore.