Just want to be prepared

So I went to my doctor yesterday for my 2nd contraceptive depo injection and she was asking me all the normal questions: how’ve I been on the first injection, if my moods are okay etc. But then she asked me how my periods had been. In the 12 weeks between my first injection and yesterday I had a 9 day period and that was it. I got my first period at the age of 11 and I’ve never ever been in any kind of set cycle with them (I’m now nearly 18): I can go 6 months with no periods and then have a 5 day one then 2 months later I’ll have one that lasts nearly 2 weeks. She said there’s quite a possibility that I may have PCOS and she’s booked me in for blood tests in a couple weeks. What should I expect from all this? I’ve done some research on PCOS but I don’t really know how to prepare myself for the possibility that I might have it. Can anyone help me out?