Feel like I'm not eating healthy enough..

I really want to eat healthy during my pregnancy but it's really hard for me. I buy alot more fruit and veg than I did before. But everytime I want to eat I always want to eat something that's unhealthy. I know if I don't have what I want I won't eat at all. I'm trying to eat as healthy as I can. Can not having alot of healthy food really cause any serious harm??