Claire, do you feel guilty because you think you should lose faster, or because convention wisdom dictates such few calories for weight loss?
In any case, if there is something making you feel like you should cut down, then why not try it for a week or two and then see how you feel? If you feel good (or weight loss increase), then assess what you might want to do. If you feel miserable (or weight loss slows), then you can go back to how it was before, and have less guilt.
Sometimes we have these worries because of uncertainty, so you can at least take that out of the picture. You aren't stuck on any one way to do this, so mess around with it for a bit until you reach your happy place!
(PS, I would be miserable, but at least I would know

)