Dont take this the wrong way mate... but IMO If you have used just filler and mesh, the crack will reappear/filler will fall out more than likely... What you couldve done was use a hot knife (gas/eletric type) or soldering iron with a flat end to melt the mesh into the bumper from behind this would be stronger, ideally you would use a strip of plastic welding ribbon also to fill the crack on the front ... or use the poly urethane "cold" welding kit (bit like araldite) then use the filler to smooth... But it may be a bit to late now sorry

Plus as the blue is just a base coat you only need to put that on in lots of thin coats just to cover, you wont get orange peel on basecoat, try helping it to flash off (loose the wetness) by flicking a hot air gun across it, use the air movement rather than heat to help it on ts way... that way it wont run, and will cover nicely, then before fully dry blow the clear laquer over 1 coat leave to flash off for 10 minutes then a double wet coat ... but be careful as that will run like a bitch