Your thoughts are clearly jumbled. To ensure I understand you, the summary of what you said consists of: You liked a girl in 8th grade, and have continued to think about her 'behind the scenes' for the last four years. You are now mature and know what you want, which is her. You wish to tell her this, and just need a confidence booster. Acting on that information, GO FOR IT BRO. You are a mature man who knows what he wants and achieves what he believes he deserves. Do it. Pull a fucking Nike.