To be honest hun, I would be starting to worry that he can't roll, isn't sitting for longer periods unaided and unsupported and isn't moving around on his own (as in creeping around on his tummy, or crawling). Could you get in to see a paed or see your GP about your options if you don't have the finances to go to a physio? Maybe there is some sort of funding or something for these things.

My kids have all been sitting and moving around by this age (crawling), as well as pulling themselves to stand up. DS2 (who is 9mths old) is begining to cruise (walk holding onto furniture or people and stuff) around furniture and can stand for about 30-45sec on his own. I know several people with bubs around this age and they are all rolling, sitting and getting around by themselves.