Dracaena - Wrinkled Stem

Hi all.
I've got a dragon tree / dracaena. I believe it is a dracaena reflexa variegata, although I'm not 100% sure. I've noticed that the stem has started to wrinkle and shrivel.
I've read everything I could find on the internet about this issue and I'm still not 100% sure if I've over or underwatered it. I've pulled it out of the pot now and gently removed some of the soil to look at the roots.

On one hand, it could be overwatered and have root rot because:
1) I have been watering it twice a week, whereas various sources suggest less than once a week watering

2) When pulling it from the soil, although the soil seems mostly dry, there are some clumps of moister soil. In past experience this soil (John Innes No2 Potting On Compost) can feel and look very dry but actually hold a lot of water in it.

On the other hand, it could be underwatered because:
1) The soil mostly felt dry. In fact, the reason I've been watering it a couple of times a week is that it seems to dry out very fast after watering. But this could be due to the soil feeling drier than it is.

2) A few leaves (but only a few) have a bit of brown at their tips or edges, which I know can be a sign of underwatering

3) Looking at the roots, I can't see any signs of rotting.

The tree sits by an east-facing window, which only gets sun in the mornings. The central heating is not usually on, but I mist it a couple of times a week to give the air some moisture.

Would greatly appreciate if anyone has any ideas what I should do!! Thanks

 

It looks alright to me.

 

The stem definitely wasn't shrivelled like this a couple of weeks ago, and I've read a lot of sources online saying that stem shrivelling is a bad sign

 

@Jules W
Long time since I saw one in person, but yours doesn't look unusual, leaves look alright as do the roots.
I'd put it back in it's pot and carry on as before, water carefully and keep an eye on the stem; it will change as the plant ages and develops. Al long as it feels firm to the touch it's probably fairly happy..
The brown leaf tips are not unusual on house plants, the air gets too dry in winter

 

All I can find is this, I expect you've seen it too.

 

Only thing that crosses my mind is, as you say the compost feels dry and it dries out quickly are you giving it a thorough watering and then letting it dry out.
Only in one of the pictures it looks like the roots are all at the top of the pot and maybe no going down to the bottom.