For All You Mom’s Out There, Did You / Do You Feel This Way About Your Children Growing Up?

I am a young mother, I am 22 and I have a 1 year old, 3 year old and 5 year old. These children are my life. I can not put into words how incredible they are to me and how much I love them. It seems I can not tell them or show them enough. I am lucky enough to be a stay at home mom and I cherish every second I have with them in their young years. The thing is I don’t want them to grow up! I lay in bed at night and worry and get so sad to know that they won’t be this little forever. My 3 year old for instance, She is so sweet, she has a very shy sweet personality and she is so lovable, I am terrified of her getting older and growing up into a teenager. I see so many children, including my self at that age, turn so rebellious and mean in thier teen years and hate their parents. I want to keep a strong relationship with my children in these years.
I sometimes think we might be ok, because there is just so much love in our house and I think maybe if we just continue like this and always talk and be open with our children they will be alright? I don’t want them to end up like me (pregnant at 15). I am doing great now, married to a hard working man, finishing up my degree in college, but the path was hard and I do not want that for them. Do any other parents feel like I do? How did you guys maintain a good relationship through the years?
I just do not see how my little sweet babies, who tell me they love me ten times a day can turn into mean hateful teenagers. Do you think that stage can be prevented?
Please I really do worry and I cry right now as I think about it. My son is starting kindergarden monday! He is growing up too fast!