How to throw away a lead

Well we're just on a roll tonight with playing ladder games aren't we?

• Platinum rank 34
• Want to concentrate on basics again, pylons and probes

I held off an early attack and built a decent army lead in this PvP.  Then instead of either just extending my lead or going all-in to finish him I got all wishy washy and committed too much to an attack while also expanding.

Match highlight:

So I should win this no problem, right?  Those force-fields and my stubbornness say otherwise.

Post-match summary:

• Platinum rank 35
• Don't get in such a hurry to finish it.  If I see colossus in this situation back off and get some air.
• Replay link