You wouldn't be asking this question if you weren't conscious of losing out to more "extroverted" brands / personas.

Without knowing the field, the business, or the details, any advice I (or others) might give may miss the mark.

You are who you are. So concentrate on changing something else.

Assuming you offer a great service or product, then your problem isn't satisfying customers; it's making the right first impression and getting them in the door.

First impressions derive from such things as (1) brand name / domain, (2) graphic design, (3) written content. Obviously that's no complete list. But maybe you can identify one of those for making improvements.