Ladies, do yo think you could help me out?

You are a decent guy. Some girls like the pessimism and sarcasm and I don't think you should change that about yourself, but you may want to consider "shelving" those a little until you get to know the girl a little so she knows it's just your personality and not you being an insensitive jerk. When talking to a girl, show interest in her and get her to talk about herself - that should help you break the ice because next time you see her, you can ask her about something relevant to her (just a little tip). At the same time, be confident in who you are and make no apologies for being 5'7" and a loner. The right girl is out there, she just doesn't know it yet. Best of luck to you.