ttc advice; late period number 2

Bronnie • 22, fiancé who we were trying for a baby cheated so now I'm single 👌🏼 live in England. Music and tattoos 👌🏼
Hi all, I really need some proper advice I'm too confused. So last month I missed my period and still not had it and I'm now a day late on the second period so that's two I've missed, however I did a test 8 days after missing the first period and said negative then I waited a while took a test sometime last week still said negative. What should I do? I'm never ever this late I have polycystic ovaries but take medication for it and not had period issues in well over a year and half so this is just not normal for me anymore! Do I carry on waiting until symptoms show or what I have noticed I need a wee more but not that much and boobs are tiny bit fuller however I could still be growing I'm 22. I have a gynaecologist appointment on the 29th I was thinking if not on by then maybe ask for blood test or scan or something to check. What do you guys think wait or? 
I had a miscarriage last august but even when I was pregnant then I still had periods..so I can never tell what's going on with me and I'm sick of seeing negatives I just want my rainbow baby. Is this my time or what? What should I do? How long has it took for you to see positives?