On rereading I'm also less convinced about changing it to third person

You must have had a reason for writing in first person in the first place, though - and I'm with Vilakins, I think it works very well. Trying to second-guess what an editor will want puts you on a hiding to nothing - it's tricky enough to write what you want well enough to please other people! So unless there's a pressing story-related need to switch to third, I'd stick with whatever you feel most comfortable with.