so, the human brain is designed to always keep wanting more - your last point may be absolutely true, and it's not even a bad thing! the trick to keep it from hurting is to learn to appreciate what you do have by practicing mindfulness. even just taking a couple minutes each day to appreciate one thing that made your day better (or even only "less bad") somehow. it's not a magic bullet, but it can help you find the more gentle "contentness" even when you are over all unhappy.
parasocial relationships are also a thing many people experience; most may not be felt as strongly as you feel for that influencer, but these sorts of relationships are even encouraged in a lot of celebrity culture (see: people calling themselves "miss [celebrity last name]"). it's also pretty common to feel like you've never really connected with someone in bpd, because the disorder affects sense of self, gives chronic feelings of emptiness, and features emotional amnesia that can leave you feeling completely cut off from even the person you love the most. there's a reason it's more common with people who have/had a rough family life, as well. does having a romantic partner define your worth or happiness, or is it maybe possible to get that connection from group settings or friends?
i'm also hearing a lot of self-judgement about not reaching your goals. could it be that you're really setting goals that are unrealistic for yourself, even if they might be considered "easy to reach" goals? could you use the SMART model of goal setting to help yourself establish more feasible goals, and get feedback on the goals you set from a trusted friend (or even by sharing them here on alike)? or, if your issue is forgetting to address your goals, could you use tools like timers, goal tracker apps, and sticky notes in prominent places to help you achieve them?
finally, you may be able to use free therapy apps (like chatowl or betterhelp) to help you stay stable while you work on finding an individual therapist. it's pretty tough to find one right now, but you may have better luck checking with your local major health systems (even if just to be put on a waiting list). if you don't like the therapist you find there, you can always use them as another stopgap until you can find a better one.
let me know if you have any questions or feedback!