Gotta think on this. I'm like a different person when I'm writing. I have time to think, and process, and choose my words. Face-to-face with me is much different...much less comfortable...much less informative. Which one is the real me (or am I someone else entirely)?
Technically speaking, they're both you. One's just more rushed than the other.
I'm like you, I've been told on multiple occasions that I'm a very "thoughtful" person, in large part because of my writing. Talking? Not so much. I'm okay for casual stuff, but I haven't learned to convey my confidence in myself enough that I don't get interrupted or ignored outright.
One of the big things that have helped me is to set boundaries and expectations in pretty much every aspect of my life. In this case, it can include something like "it takes me a little longer to get my thoughts organized into words, so please allow me a little extra time to respond to you." This can buy you the time to "write" your response in your head so that you can speak it. You still don't have the luxury of going back and re-wording things, but the extra time might be sufficient to make interactions a little easier and more positive.
Instead of thinking about what you're not or what you fail at, think about
what you need to succeed. This will likely be an evolving thing, but it helps a lot. One of the early things I did this with was my job. I've bounced from job to job for years, in part because I didn't take into account my own needs when taking jobs. I had a good list of what
wasn't good for me, so I used that to figure out what
is good for me. I then wrote them down, and whenever I talk to recruiters or whatever, I make sure that my needs are known, and I explain that those are my needs in order to be the best employee that I can be. You don't have to start there, just find a segment of your life that seems to lend itself to this type of analysis and go from there. A little while of doing this in that segment, and the behavior started bleeding over to other parts of my life, and my life has been better for it.
I will say this -- you very well may still "lose" people in the various aspects. However, that is not inherently a bad thing. The ones you will lose are going to be the ones who are toxic for you to begin with. The remaining people are the ones that are actually worth your time (yes,
they're worth
your time, don't think about it the other way around).
For example, making my needs known for looking for a job means I discard easily 80-90% of the stuff that comes into my inbox (recruiters, leads, everything). This is because I've determined, using the criteria that I've written down, that these items, people, or companies are not worth my time. We're not good fits for each other
and that's okay. It saves everyone time and headache, and lets everyone move on to someone or something that better fits what they're looking for. And the 10-20% that I do keep? They value and respect me that much more, and provide higher quality interactions.