How to be more aggressive?
I main Ahri mid, and secondary Tryndamere top (I also play Lux, Orianna, and Nasus). I commonly will gain a huge lead, and do really well, but still end up losing. For example, as Ahri I was 6/0/4, but ended the game 10/4/10 and lost really bad, because I was the only competent one on my team. Now normally, my team isn't completely full of retards, and there's at least one other person who's okay, but then it seems like a 50/50 chance of winning. It's not like the enemy team has anyone who's really good, so I was confused as to why I couldn't carry.
In said Ahri game, the enemy Sona said I was really good but that I needed to be more aggressive. After giving some though, I did some research into higher elo players thoughts on play making and how to carry, and decided I needed to be more aggressive overall.
Normally, I play it safe and just harass until my enemy makes a mistake then I punish them (normally by killing them). This gives me a huge lead, but doesn't do much as far as the overall game plan. Once I get this lead, how can I be more aggressive and ensure that my team can finish? Thank you for your time!
(Oh, and if it matters, I'm Bronze. Currently Bronze 3, about to hit Bronze 2. I'm climbing, but it would be faster if I were better at carrying.)