Stripped oil drain

New to forum and hoping for some help please,
recently acquired kz650 csr 1980 in need of some work .
Decided to change oil , why wouldn’t you !
This is where problems all started , the drain bolt was stripped and won’t come out , removed oil filter okay .Decided to remove sump to get repair done and not sure why I can’t get get it off .
Have removed all visible sump bolts am I missing something apparently 2 bolts under starter motor not there I’m desperate help please 🙏 

The gasket has 15 bolt holes so if you have removed 15 bolts and the oil filter bolt it can only be sealant or corrosion holding it now 

Thanks Wookee , great help been looking for 2 extra sump bolts suggested byAI for 2 days ,
should know better than to trust it .
Still at least on the wrong road it sent me down I managed to remove the starter motor and side casing I didn’t need to .
Such a relief to get sump off after a few taps with a wooden drift , can’t say the wife was so pleased about the flood of old engine oil on the patio !
many thanks again I’m sure I’ll be asking for more help on the forum soon 👍