The main problem I was having was spawn larva injects finishing and OLs not being done. So I'd be supply blocked with like 8-10 larva just waiting on an OL to finish. This was a problem even with making lings, but with making roaches it was horrible. Also, with the injected larva building up, I'd have an OL spawn just to make a ton of units and be instantly supply blocked again.
I'm trying to figure out this timing, still. I know 1 OL at 9 is fine. 1 at 15-16 is fine, but once those 2 queens are out and vomiting goo all over everything, it seems like I need to be spawning like 2-3 OLs at a time anytime I'm within 8 of my current cap. Is this accurate? Do I need to stay 2-3 OLs ahead of my supply to be safe?
Oh, and that's not even considering OLs that get picked off by the enemy. Forget about building anything at that point. :/
I know it was 'worse' but life seemed so much easier when I was just building till capped then making like 3-5 OLs at a time.