There are many variations of pec building exercises.
Take the bench press, using a bar over dumb-bells calls into play other secondary muscles which will work in one way to stabilize the dumb-bells differently than the bar.
Then your incline - angle that you lie to the direction of gravity will slightly impact different parts of the pectoral muscles.
If getting a big chest is the issue, there are exercises that slowly expand the ribcage. https://www.google.com/?gws_rd=ssl#q=exercises+to+expand+rib+cage
has lots of sites that discuss that.
How often? The general rule of thumb is every other day you can work a muscle.
That is a general rule of thumb. Some guys find that ever third day works better for them as their body requires more time between workouts to recover.
The only exception appears to be the abs, they can be worked everyday and appear to recover in half the time.
How many reps and sets depends on how much weight you are lifting and what your goal is.
Two goals in general are mass building and 'sculpting' where definition, shaping and endurance comes into play.
High Weight, low sets/low reps = mass building.
Low Weight, high sets/high reps = sculpting.
Its a general rule, some guys discover that their muscles respond differently and get varying results.
As for diet, it is crucial to your fitness goals. Muscle requires things like protein in order to get bigger and stronger. So a diet higher in protein is kinda required.
I have no idea why you are single... Perhaps because you are young and haven't meet every man in the world yet? Maybe because your circle of social activities to meet new guys thus potential partners is small?
Perhaps you are too cute for your own good and that causes guys to not approach?
Perhaps when you open your mouth your pearls, purse and Channel fall out and causes guys to run?
Perhaps.... There are a lot of potentials.