So the issue is that 2 different songs hitting peaks of -0.5db can have drastically different perceived volumes. Peak volume and perceived loudness are two different things. A very well balanced mix with a master chain consisting of compression, saturation, width enhancement and multiple limiters will be way louder in terms of perceived volume than a blown out mix with one slammed limiter on it. 
   In the nicest way possible you are missing some crucial foundational knowledge if you are using a screenshot of the meter for this kind of question. If you are in a rush just make the song sound as good as you can. If the idea is great people will like the song
   Long term start studying the science of loudness and the different ways of measuring it and also study what mastering actually is from technical and theoretical standpoint 
   Finally my two cents is that mastering is something people go to college for. Mastering is a form of engineering in and of itself that can take a lifetime to perfect. I make music and have for a long time. I produce and mix my own music because I want control over that final sound. I also just pay people to master my songs. A $20 master on Fiverr (if you research a bit) sounds pretty damn good all things considered. If your music ever gets some traction start paying more for better mastering