I too have many of the same struggles. I often try to justify it by putting it down to my personality, or to depression. I even think to myself that God knows how I'm made and that it isn't my fault I have no self discipline.
When it comes down to it though, I know it's me giving in to me all the time.
I know what I SHOULD be doing to make things better but I don't want to do them. Again that is down to my own choice and, whether I think so or not, I AM able to make a choice for the Lord and not for myself.
I saw something recently that said "God of new beginnings, here I am again" and I felt that it could have been me saying it.
All this makes me wonder the same as you said, "How can I be a real Christian" if I prefer to give into the flesh all the time. I DO know that I am saved but I am missing out on so much by not attempting to stay near to God.
Thank you for sharing; it was good to know that I'm not the only one struggling with this issue.