Re: Over level 500 and still no heirloom shards
your level has nothing to do with the Heirloom's.
You will need to calculate how many Apex packs you have opened. If you do not receive a heirloom from opening Apex packs before opening the 500th Pack you should get one as soon as you open the 500th pack.
There is a Pack calculator online you can search for. I do not have the Link but have used it.
I hope this helps you out.