My girlfriend is 28 and I'm 18... should I carry our relationship on?

My girlfriend is the best thing that's ever happened to me. I won't go through every good and bad moment we've shared, but, although we have been together for only 10 months, the time I have spent with her has been the happiest time of my whole life.

At the beginning I told her I was 19 when I was only 17 at the time, as I thought she would more seriously consider dating me as she was 27 at the time. This was very wrong of me as I should have gave her the option to decide whether or not I was too young for her. After I had met her once or twice and before she found out my real age, I was sure she would refuse to continue to date me once she found out the truth so I never really took us serious (we also weren't in a relationship although we had slept together once at this point) and I slept with two other girls. I told her all of this as soon as we got serious and although she was understandably upset she accepted it. I also watched porn for about 2 weeks of our relationship during a very rough patch and I confessed this to her and she was extremely upset.

They are all of the bad things I have done in throughout our relationship. I wake up with her at 6 o'clock ever morning to make her breakfast and lunch for her before work, then walk her to the bus stop. I arrange very romantic dates and nights together and treat her as well and pure as I can. I really do try my best to be the best and most caring boyfriend I can be, and she really sees that and appreciates it. The problem is she can be very disrespectful and hurtful towards me when she gets depressed, she can be extremely hypocritical and controlling (e.g. she becomes very irritable and disapproving when I eat fast food because she is very healthy, yet she smokes cigarettes which I really dislike and have never enjoyed although I have always been understanding and accepting towards her needs and wants) and I have felt like I am always putting in all of my best efforts to make her feel great but she seems to do what she wants and controls me. I feel like she has lied about a few things which she refuses to tell me, although I'm sure she's never been unfaithful. Our relationship can be REALLY great a lot of the time, and I'm willing to work at the bad things to make it all work.

The problem is she is 28 and I'm 18. I don't want to get married, have kids or get a house yet. She does want a house but has told me she is willing to wait as long as she needs to for me. She said the same thing about children. I love her very much but I'm afraid something could happen between us in the future and I will be absolutely fine to start again but she could be 30 or 32 years old and it will be very difficult for her to find someone to settle down with and have children with... the thought of which makes me feel sick.

After a long think, I made the most romantic night ever a week ago and left her with a letter in her draw explaining all of this to her. I wanted to have an amazing memory to think back on and remember about us that we won't ever forget, but I didn't want to risk leaving her in a vulnerable situation in the future. I love her and I have cried every night for a week reminiscing our amazing times together, wishing we could be falling asleep together again. The only thing stopping me from going back is that I don't want to be selfish and going back to her with the idea in my mind that we might not spend out whole lives together... am I right in thinking like this? If I wanted to be completely selfish I never would have done this in the first place and we would still be together today. I just miss her so much :(

I don't think I will ever find anyone who understands and loves me as much as she does... I don't want anyone except for her... I feel like the right thing is to keep strong and stay away from her for a while... but I just miss her so much. Any thoughts on the matter? Please give me your input! Thanks a lot.