Spaceid, I have a boyfriend who is hard to read as well. Please, don't worry about him not asking further about your day. Most guys I find take you at your word. You weren't feeling well probably meant you were ill, so he didn't need to ask more.
*hugs* As for not being able to tell him what you were feeling, or that you're depressed, that may take time. It is so hard to get that out. Hopefully once you are able to explain you'll find more support from him.