First vs. third

Ooh! I know!

Use 1st person when you can, and when the viewpoint changes, use 3rd.

It's possible to change the POV character when writing in first person. It's not too uncommon to change character like this every chapter.

It helps to make it nice and clear who's POV you're writing from though, like by giving the character's name in the chapter title.

So make a new chapter that is only a handful of paragraphs long. ^_^ There's no rule on how long chapters have to be.