Hair changed texture after bleaching

Is it growing back in fine and thin?  I have never heard of anything like that but if that is happening to you you should probably see that dermatologist again.  To my knowledge the only thing that changes hair texture permanently is chemotherapy.

If you are talking about the hair that was actually fried by the bleaching you may need to cut a lot of it off before it will begin to behave and look better.  Really damaged hair breaks off and it usually breaks at the point where the fried hair meets new growth.  That may be why it appears thin to you.  It is actually much thinner since you have lost a lot of it due to breakage.  If you cut it shorter it may slow the breakage as there will be less weight on each strand.  You can also try using deep conditioners every day.  My daughter did that after a particularly bad episode with bleach and after a couple of weeks her hair looked and behaved much better.  I have also had that same experience with perms.  The best thing to do is cut as much of the damage off as possible.  At least you have had five months of new growth.  That is a real good start.