I need to number atoms using `chemfig`. I thought I could use `\chembelow` and `\chemabove` to place numbers above and below but adding these commands changes the look of the drawing and does not simply only add the number. 

```
\documentclass{minimal}
\usepackage{chemfig}
\begin{document}

\chemfig{*6(\chembelow{}{1}=\chembelow{}{5}-\chembelow{}{9}(*6(-=-=-=-=))--=\chemabove{}{2}-)}

\end{document}

```

![Chemfig example](https://i.stack.imgur.com/8e1fp.png)

The lines are broken where the numbers are added. How can I add numbers without breaking the lines? Also, the numbers are placed very close -- could that be related?