You are not training hard enough.

A couple of points:

- You should feel like you are freaking dying, not feel a bit heavy
- Since you go to a gym, get someone to spot for you if you are using barbells. If your gym allows you to drop the DBs, just drop em
- In terms of difficulty, Dumb Bell is the hardest, Barbells is 2nd hardest, Machine is the easiest
- Therefore, I would suggest you go up to DB 15kg (each), BB (if available at your gym) 35kg and machine at least 40kg
- IT NEEDS TO FEEL REALLY HARD. By rep 5 of your first set, you are already sweating like crazy
- You probably have form issues with your DB press. You may be using too much shoulders (front delts) instead of chest (pects)
- If you feel the above point is your bottleneck, check back with us
- (Controversial point) I would suggest skipping the benched chest fly, can lead the long term shoulder issues. Instead, use the machine version or cabled ones. I also dislike the smith machine version, the form feels yuck

G'luck with growing the cup size