I'm in a similar boat where I'm not an enthusiastic/chatty person and it can come off as uninterested. But there's hope, here is how I cope.
- Generally accept that people prioritize where their interest is and the vast majority of the time that would be their ship or potential ship.
- If you post regularly and reliably people have more trust in you (I'm failing this right now due to Baldur's Gate).
- Be adaptable with plotting. If my partner likes to pre-plot I'll pre-plot. If they're all quiet on the western front then I wing it.
- Read your own post as if you were the other person trying to respond to it. Did you give them enough to go off of, without overwhelming them? If not, edit.
- Sometimes you just don't have chemistry with another person's writing and that's OK.