flowers usually have a very soft look which looks great in watercolor. not that deep into that topic myself but i would try to blend the yellow more softly. right now its kinda patchy. lightning itself is hard to tell without seeing the image you used as ref.
This is gouache, which seems to me even harder to get smooth than watercolor. Maybe with practice I’ll make better progress with it. So much to learn, so little time!
Like your tulip. As for shading a yellow flower, I mix purple with yellow to get a nice shadow. Same goes for a yellow pear, mixing purple with yellow for the shadow. Hope it works for u.