A few things here...
First, I think the difference between you and your male peers is maturity. You're much more mature than they are and you should take that as a compliment. Continue to seek a true meaningful relationship as you are and don't worry about being different than your peers. Yes, you may feel lonely, but sometimes in life (especially in today's broken culture) you're going to be alone when you're representing what is right.
Second, work on your self-esteem. It's going to be hard finding someone to love you if you haven't learned to love and accept yourself. It sounds like you have a good heart for your age already, so you're off to a great start. If you're bothered by a little extra weight, then work on it. Don't feel like you need to have a muscular physique, but maintain a good, healthy weight... you don't wan't to work your heart out too much.
Next, if you don't have a hobby or you're not involved in an activity you enjoy, then find one and get involved. When you do, you'll end up surrounding yourself with like minded people. That will produce friends and potential girlfriends that share similar interests.
Finally, trust God :) God created you and loves you so much. If you seek a relationship with God, God will never leave you nor forsake you :) God's the best friend you'll ever have!