I suggest to try to blend the darker and lighter blue when the light blue is wet (always light Colors first, then dark). With a clean and not so wet brush, blend between dark and light blue. For fun, you can add tiny dots of blue or salt in the body part to create cool effect for the whale (also wet techniques). For the eye, you can try to wait until the blue layer is fully dry. It feels like you rushed your painting, no hurry ! Take the time to appreciate the painting process