I feel like a terrible mom already!

Okay I am a FTM and I'm 21 weeks 3 days pregnant. At the beginning I was doing good no caffeine, eating mildly healthy and felt ok. Then i got really sick and ate only crackers and bread. Now that I'm further along I have been craving caffeine and pop and sugary stuff. I drink coffee in the morning then drink 1-2 12 oz cans of coke a day and also eat a lot of sweets like chocolate plus I have had such bad depression I cant even cook or do anything really :( on top of that I have been trying to quit nicotine and it has all been really hard on me. Please no negative comments as I am trying really hard to better my habits but please tell me I am not alone :(