Quick question?

So my boyfriend and I are always going back and fourth on the months lmao I get confused since my doctor just goes by the weeks.. So if I'm 22 weeks how many months pregnant am I right? I thought I just hit 6 months and at 27 weeks u start your 7th month.. But he says I'm not lol who is right? help! ( or if anyone has a picture of the calendar and how it works) I know some months are 4 and some are 5.. Something weird like like that