I suggest that you try to find some plastic bins that are almost see-through and fit the space. That would be two for each of the lower shelves. You could pull out the bins to see what is inside and even label the outside. Or you could cut your plywood to fit the space and support it on the built-in shelves with bricks or purchased legs. The problem with this is that things in the back would be even more hidden than they are now. Then for the upper left you might be able to find a set of shelves that would fit. For the top right, I would put big soft things that you can grab and that won't hurt you when they hit you on the head! This might be extra bedding, towels, out-of-season clothes. For children's clothing I like to fold the whole outfit together, so that one doesn't have to hunt for the "matching" part. I think that your cosmetics could be in a small box that fits on top of other bins or clothing on shelves. Good luck. This will take some experimenting, but something will emerge.

I have a deep pantry too, I have slide-outs and baskets both. I used the baskets because I'm afraid the slide-outs will drop canned corn on my toes or something.

I think the kitchen you posted is really cheerful, young and full of energy. Nice retro feeling. It's interesting to compare it with the one below that I just found on Houzz -- which I must admit is closer to what I would choose if I were going green and yellow. But then I'm neither young nor full of energy. I love that there are so many different ways to do things. (I have to admit that in the one below I don't think the blue/turqoise accents work too well.)

Plan the bed on the T.V. wall. You can start from the window side. The sequence will be first the dressing mirror with 2' wide dressing unit then 6' wide bed next 2' wide night stand. By providing the dressing near the widow, you'll have the advantage of natural light. On the opposite wall make a drawer chest or the study beneath the window next is wardrobe. Plan the wardrobe in such a way that you can provide the T.V. unit centering the bed. This way you need not do any structural changes and it fulfills the requirements also. Never compromise with the wardrobe depth. You must provide 24" depth for a perfect wardrobe.