I am installing 20" porcelain tile in my bathroom to a house we just moved into. The carpet was removed and the floor allowed to dry from it...yuk! I removed all the staples and cleared out the glue from padding. The floor was level. I put thinset and used 1/4" trowel at 45 degree angle. I mixed the whole bag to make sure of the proper ratio...best mix I've ever had, nice and smooth. Put down the hardibacker. (day before layed out all out for proper cuts so it would be a straight layout when using thinset). After screwing it all in yesterday, today, being less exhausted, I am noticing that the sides are not level in one place on between two sheets. Can I use more thinset on top of the cement boards and work it the same as I would on a wall? Or do I have a bigger problem?

Thanks for any help anyone has to offer.

The room is a little over 100 sq feet