I agree that it looks rather like H. bituberculatus apart from the colour of the legs and the size. There is a finite possibility that it is another Hylaeus species but think H. aralis is the most likely.
I think this is bigger than H. aralis it was about 8mm. The flowers in the image are a cultivar, I think it was called Michelle, it has enormous flowers, the platform the bee is standing on is 10-15mm wide (bigger on older flowers