Uy, three months delayed is really worth checking with your doctor na, sis, please don't wait pa! Even if your PT tests came back negative, there are lots of reasons for delayed periods (stress, hormonal changes, thyroid issues, and marami pa) na kailangan talaga ng professional to figure out, hindi lang pregnancy. A few of my mum friends went through the same worry, and nakita ng doctor nila agad kung ano ang nangyari, mas peace of mind, at nakuha agad ang solusyon. Please make an appointment this week, ha? You deserve to know what's going on with your body.