Uneven hardiebacker on victorian terrace bathroom floor

[Ross tile]

Hi there - so i have ripped up the old tiles and old layer of ply and cork. Replaced with 12mm hardiebacker screwed in along with a layer of adhesive between the backer and the floor. There is some discrepancy of maybe 5mm between aome of the boards. Do i need to start again? Im using flexible adhesive and the room is around 1-2m2.

Current plan has been to rip up the problem boards and reapply

Any advice would be great!

 

[Ross tile]

Thanks for all the replies - i've attached a photo for a bit of context. So currently my plan is to put down the rest of the HB as most of it has already set and is flat, seal the joints using cement board tape and adhesive, seal up the area with battons / expanding foam around the skirting board / door / pipe holes in floor, apply self levelling compound, hope for good results and hopefully get tiling this weekend.

This is beginning to feel like it will be a very messy job but hopefully its reasonably straightforward. Feels like a lot fo effort for such a small area but may as well do it right