Learning Qiyana - and other things

I have really taken a thorough enjoyment to the champion qiyana. I played her a lot in twisted ranked (to get slightly more competitive players than norms on SR). But I need some helpful input on how to improve areas of my game, especially as her.

1. If you are falling behind as qiyana, is forcing ganks when ult is up, or just steady farming a better choice? I had 2-3 games where I went like 1/4 and 1/5 and I felt lost on what the better choice to do was, because at that score answering the roaming mid laners felt futile, but then teammates would holler and spam their ping button as hard as they can.

2. Is their a better way to execute a combo with her? I typically in a melee fight Q, W toward terrain, throw a q out toward them, e threw them, ult them into the terrain, and then have enough time for auto and one last Q to kill. Is that the most optimal combo as her? Or is long term fights with her on hit damage better and just wait to close out the fight with her abilities?

3. Is she actually good? I loved diana for a long while, but the way qiyana feels. It just seems a lot better because my ult and river element offers CC that actually contributes to team fights, versus diana that blows her load, kills the adc, and dies because everything is on cooldown (unless you hit like 3-4 champs with the Q).

Any additional tips to know would be greatly appreciated. Thank you.