It's not weird, it's just wrong. If you were both adults then that's fine, but you're both minors. She is still a child, she is not a teenager yet. She most likely hasn't hit puberty yet or is only at the beginning stages. You are a teenage boy. You're closer to being 18 then being the same age as her. You've already hit puberty, and knowing how guys who are going through puberty can get, they should not at all be with a young girl. A four year age difference is too much of a gap for minors. In my opinion, an age gap of 3 to 2 years is appropriate.
No. If other people think it is, it's only because they are single. Just let it roll off your back if other people think that it is weird. That's kinda how I was, except the girl wasn't a girlfriend. She's in 6th grade now, and I'm a freshmen, but it was last year. People kept bothering me about it so much and I let it get to me when I shouldn't have. But no. It's not wierd.
When I was 11 I dated a 18 year old its basically the same thing I'm 14 almost 15 and yes I'm in a relationship and y boyfriend is 15 he turned 15 not long before we got together. I'm not trying to be mean or anything but honesty it is weird it's like dating a younger sibling. At 11 you really don't know how a real relationship works and you won't realize it till your my age..