Gap problem with fill

when I use the fill tool with grease pencil it keeps filling behind the shape I’ve drawn. how do I fix this. Any help is much appreciated

Maybe this (fill tool)
https://docs.blender.org/manual/en/latest/grease_pencil/modes/draw/tools/fill.html

and specifically this, (fill tool > filling areas) might help:

https://docs.blender.org/manual/en/latest/grease_pencil/modes/draw/tools/fill.html#filling-areas