Hi Jen and
to the forums!
Your Pico is a very handsome little guy
I agree with Deborah completely. Your little one sounds like he couldn't be happier and loves having you both all to himself!
My little girl Mallorn is the same way, she's three now but has lived with us for almost four years and is very happy being a solo budgie. She loves the attention she gets from everyone and her bond with me is something I treasure immensely. I wouldn't ever consider getting her a friend because I don't believe she would benefit from it at all; apart from liking her own cage to herself and having her "alone time" it's just not a necessary component of a happy life for her.
Also, he doesn't look in the mirror a lot because he's lonely, he's just interested in the bird he sees "on the other side". Even if you had a wonderful life, if you saw a human every time you passed through a "window", you'd wonder what they were doing there, too
In fact, solo budgies really shouldn't have mirrors as they can develop an unhealthy obsession with them over time, leading to stress, aggression, and withdrawn behaviour that can negatively impact him as well as your bond.
I hope that makes sense
As Deborah said, though, if you'd still like to get another budgie, you can do that as well, although the dynamics will change significantly.
In the meantime, be sure to review all the links provided to you by Deborah and be sure to ask any questions you may have afterwards
Hope to see you and your darling boy Pico around the forums!