You have a lot of good advice above, but one point in your post caught my attention. You mention that your shots are "washed out". To me that would indicate that the problem you have is thin, flat (no contrast) negatives. Not that you have any fogging problems.(posted 8342 days ago)I have started teaching darkroom work and it has been very interesting to see a lot of students working in B&W for the first time. The most common problem that I see is underexposed film. Underexposed film requires more development to increase contrast.
My first sugestion would be to forget the 25A until you are getting better results without it. Go shoot another roll of film. The entire roll should be shot under similar lighting. Shoot the first third of the roll with the film speed set at 400, the second third at 250 and the remainder at 160. These are broad steps, but will give you a good idea of where your true film speed will be. Process this roll exactly like you did the last. See if the alternate settings look better. If the over exposed frames look better that the first frames, you can either adopt this new speed for HP5, or do some more experimantation with longer developing times.
In any case, make sure that you come back here and let us know what you have discovered.