I also live very close to Walton. You have the issue there that people have to choose whether to live near the station or town as you can't have both, but that's an issue with the location and you can't do anything about that... Like others have said, you've actually got it on with one of the best local agents (we bought and sold with them) so I doubt you'd do much better with another one, sadly.
As everyone else has said, you need to sell why you bought it. Have the windows open - can you open the Juliette balcony and make a little "garden area" ... Or show how you've easily been WFH etc? Just looks like there's a few sofas and a TV in the reception room? Why don't you have a little bistro table to eat/work from? Or do you do that from the breakfast bar? I'd also consider moving the furniture so that one of the sofas is in the middle of the room and getting a rug so it's clear there's enough living separate space.
You've also mentioned storage elsewhere - that needs to be included with a photo if possible. And again, where do you park your car, if you have one? Even if you don't have a car then a passage about the (hopefully) ease of access for parking permits/private underground car park or whatever wouldn't go a miss.
Aside from that, now just isn't a great time to be selling a one bed flat within commuting distance of London. If you can even call 20 mins walk to the station "within commuting distance" - I wouldn't. People who need to use the train won't look at it as they'll think it's too far away and then people who don't need the train are moving further out to the coast/north and ditching the previous London fringe hot spots all together, where they can get more than a small one bed flat for their money. But aside from holding out and/or selling at more of a loss there is nothing that you can do.