Age is just a number. I don't think there should be restrictions. Naturally the gap does get bigger the older you get. When you are a teenager one year seems big, but the older you get the more you realise how silly the idea is:
My history:
Me: Her
13: 13 (lasted 8 months)
15: 14 (lasted 3 months)
16: 15 (lasted 1 year)
18: 18 (lasted 3 months)
18: 15 (lasted 2 years)
21: 17 (lasted 6 months)
22: 16 (lasted 3 years)
26: 18 (lasted 1 year)
30: 19 (lasted 1 year)
32: 17 (still together happy)
If you are both happy why should it matter. Forget about the stupid rules society tells you.