relax mate
your problem looks like clogged radiator
make sure radiator is clean from outside
no dust or leaves around the tubes
no external leaks whatsoever
checking head issues :
by removing radiator cap , run the engine till warm
and rev suddenly and see any jets from the radiator
or smell of combustion gases
or bubbles while idling
any of those symptoms would be head issue
if you wana spend money , take it to service centre and do compression test
any compression drop , know from where exactly

if you go with radiator replacement , do not forget fitting new rad cap
and overflow line going to expansion tank (erba) is good not blocked
all lines from radiator neck till expansion tank should be tight , clear , clean., including the little hose
under coolant surface in expansion tank
I hope it is helpful