I agree with Suzie on the dispersement of the black and white prints. Visually the blacks and whites are balanced diagonally but the scale of printed dots is visually top heavy. Another words my eye is drawn to the top half of the block. Here's a little trick... squint your eyes to let in very little light and then look at your block. Ask yourself what stands out? Is your focus stuck in one place or are your eyes traveling to take in the whole? If you want to stay with the dot theme using only those four prints, my suggestion would be to combine the two whites in a strip pieced or other simple block, do the same with the two black prints, then lay out the darks and lights diagonally as you have done in your original. This would even out the overall look by spreading out the values and prints. The contrast is strong and appealing in your block and I love how you dispersed the purple onto the other blocks. I would have enlarged or increased those dots in the bottom two prints.
The beauty of working with black and white is that it helps train your eye to see value, contrast, texture, pattern, line etc. without the additional color distractions. Thank you sistahdebbra for sharing your piece and allowing us to hopefully critique in a constructive manner. Keep playing and have fun with it.