Tivaniag- oh man i am soooo sorry you have had such a terrible experience! but honestly in your case i think you are safe to wait a few more days and try a few pain relieving tips first.
If you start bleeding heavily, getting a foul smell or are literally bent over in pain all day then definitely just go see a different gynae at a different hospital. Those are pretty good signs that something is seriously wrong.
If your scar starts to appear pussy or infected, badly swollen or very red around then i would say that should indicate an infected wound.
You just had major abdominal surgery and on top of that you need to care for a newborn who is not sleeping well and an older child, you are going to be pretty uncomfortable and sore for a while and 19 days is still very early. Try to make yourself as comfortable as possible at home by making sure your bed isn't too high or too low, keep lots of pillows behind you in bed so when you get up for baby it's not such a struggle, make sure your chair or sofa is a good height for you to get in and out of without using stomach muscles because every strain will set you back a few days in mobility. Make sure you're holding a pillow or putting some type of compression over your abdomen when you laugh, cough or sneeze because a sudden jolt can pull a sore muscle.
I hope the pain goes quickly but as your not breast feeding i think maybe you should get some Pynstops or speak to your pharmasist on the strongest OTC meds and see if that doesn't help.