Your situation is very close to mine! I've been here 4 years on a 417, and 2 457s (first job was made redundant but the company redeployed and sponsored me in another similar role). Just applied for my 186 and hoping for a quick grant so that I can get paid parental leave when my baby arrives (though unlikely but stranger things have happened), my partner is Aussie so we can get the baby bonus if ours comes 2 weeks early as it is being scrapped come March 1st!!
Hope you get your grant very soon