Don’t understand...

I have a scheduled c-section on Monday April 8th.. Monday I called my OB because I’ve been having contractions and my back I believe I’ve been experiencing back labor as well.. they asked I come in for a NST which indeed confirmed I am contracting 1-2 minutes but the doctor said they are not strong enough since then at night time my feet, hands and face have been getting really swollen... what i don’t get is why make me wait for the c-section instead of preforming it a few days earlier, I was told at last ultrasound baby was already weighing 7 lbs 13 ounces (that was 2 weeks ago)