First, I'd suggest you take a deep breath and quit beating yourself up! Now matter how advanced of a quilter you are, you'll have things that frustrate you from time to time, and this is one of those times.
I starch and iron before I cut my strips, not after. There's a lot of room for distortion when you're ironing, especially if you're starching heavily enough that the fabric feels wet. Even more so when you're ironing something only 2 1/2" wide.
I understand hating to iron a large piece of fabric; I also hate to iron. If I've bought multiple yards of fabric and I only need 5 or 6 strips, I will cut off the approximate amount I need, iron that, and then cut my strips. It's a lot easier to handle.
I make sure that once I have the approximate piece of fabric cut I iron out the crease then refold it selvage to selvage so it's perfectly straight. You don't want to put the crease back in fully before cutting your strips.
A couple of points about ironing - I use Best Press and prefer it to sizing. It really helps get wrinkles out with a fairly light spray. I've never had my fabric feel wet before pressing.
If you hate ironing because of the standing involved, lower your ironing board to chair height and sit while ironing. I find it much easier.
When you're cutting the strips be very sure that your mat is on a nice even surface and you are holding your ruler firmly in place. I've found there were times when I was pressing down so hard on my rotary cutter that I'm moving the ruler. Firm steady pressure on the rotary cutter is what you need. Keeping your pinky finger off of the ruler and resting on your mat can help you keep the ruler where you want it.
Lastly, it may help to have someone else watch you as you do your cutting. They may spot something that's causing your inconsistencies.
Hope this helps!