Starving 24/7

So I'm only about 6 weeks right now but my appetite is out of control. I am literally hungry all the time!! I'm trying really hard to make healthy choices with what I'm eating but it's so hard and nothing seems to fill me up and I don't want to resort to unhealthy things. What can I do?? Is it okay to use like meal replacement shakes or things like that? I just can't stand feeling this hungry all day. I'm use to only eating a little bit throughout the day and this is crazy. HELP!