I think you need to add something to the utility to make it look like a utility (now I realise it's a utility it's a great size) as I also assumed it was really dark kitchen. Get rid of the mix of pictures, maybe put in a plastic plant, and some bits that look more like a utility, such as an airer, laundry basket or ironing board. We normally say declutter for pics but I think you need something to show the use and what a great asset it is to what looks like a tiny house. Maybe some big posters about laundry, probably something you can get cheap at home bargains or the range.
Hallway is lovely and big and bright.
Lounge is lovely, but pull out the table and chairs as it looks very squashed in the photo.
Kitchen looks great and a good size, and well cared for. Maybe remove the dog crate though, for the pics. I'm put off buying a house that has a dog, but if you hide the evidence of a dog I might look round and fall in love with the house.
Garden I'm afraid is possibly the problem, but saying that you've done it nicely to the best you can given the steepness of it. Maybe a photo from the back of the garden looking at the house to show you've got a decent flat patio before the steep bit.
Bedrooms and bathroom look fine. Maybe the smallest room would look bigger with a normal height bed rather than cabin bed, but obviously it shows you can still fit a bed in there with room to spare.
Is the loft conversion done to regs? I think that's a real selling point as it looks quite big.