Aloe Peglerae Help

[Stu77]

I'm looking for abit of advice with my Aloe peglerae...
When I purchased it the leaves were all very plump but now the central leaves are starting to get abit skinny and I'm not sure if I should be doing something different with it.
Up until two days ago it had lived in my south facing window getting a fair amount on sunlight but I have now moved it Into my greenhouse.
I repotted it shortly after purchasing it as I though it might want a larger pot, I went from a 7cm pot to circa 12/14cm. Could the large pot be the issue?
The soil mixture I am using is a equal combination of john innes no2 soil, horticutural grit and horticultural sand. I am watering it once a week ( I'm wondering whether that might be too frequent?)
Can anyone tell me if I'm doing anything wrong or give me some advice please?

[Stu77]

Here is a picture of it.
The middle leaves were once fat but are now quite slender.

[greenknight]

I think the light it was getting on the windowsill was not sufficient.