Many a young woman would feel like the luckiest person in the world to be with someone who is happy and peaceful and who loves themself. I don’t know where you got the idea that a woman needs a muscle man to protect her. What they most want and need is someone who is loving, supportive, trustworthy, and who shares her values. More important than the ability to physically fight is the ability to forge a working team with your partner.
You are not at all alone in feeling insecure about your ability to be a partner. At 19, it is normal. I assure you, most teens go through a period of self-doubt and insecurity. Most also don’t want to talk about it because they are under the impression that everyone else has figured it out. They haven’t. They will. So will you.
Please relax and be the happy person you are. Take part in things you enjoy where you will meet young women who like to do them too. Friendships will naturally develop. In time, one of those friendships may evolve into something more. You have plenty of time to find the right woman for you.
I wish you well.