A little help please

I have managed to build my own quadcopter, admittedly not expensive parts etc. everything going well until it came to flying.

My first flight i managed to get it off the ground about 6ft, i was barely touching the pitch and roll, just to get a feel for it. All going well until the prop nut flew off and the drone crashed. Oh well scratch that one down to experience.

One of the props was broken so ordered a few spare ones, unfortunately I thought they were coming from the UK, but no, Chinese company with a UK address, so they finally arrived a few weeks later.

Unfortunately the motors have an 8mm shaft, but the props came with 6mm or 6.5mm. So I drilled out to 8mm. They were tight, but I used the prop nuts to tighten them all the way down and they are now solid.

So went for a test flight again, and the above might not be relevant, but when I arm the quad, motor 3 starts spinning, and the other three don't spin till i move the throttle. I push the throttle to somewhere between 45% and 50% and the motors actually slow down (I can hear it). Then they start accelerating again, so I pull the throttle down to get control again.

So when I try to throttle back up it will take off, but wants to tip forward so I immediately throttle back down. At this point its like the ESCs reset themselves as the motors switch off and the Flight Controller goes into disarm state and won't arm again until I pull the battery and connect it again.

As I said the props might be a red herring, but two of the motors took the brunt of the initial crash. I bought really cheap props, my thinking being they are the one thing I am going to destroy most while I learn to fly this thing.

I did calibrate the FC through mission planner, and also individually calibrated the ESCs using the throttle channel connected to the ESC method.

So a bit despondent at the moment, so any help would be appreciated.