Trying to conceive last 3 months. Such?

I'm 5 feet tall 68 kg . My periods are regular 26-28 days duration. I tested with ovalution kits & im ovaluting. I have mild pcos but all harmone levels are normal . I'm taking flo 123 prescribed by my doctor . When we try to conceive in fertile window , I'm seeing lot of changes happening in me . Like post that my heart beat rising rapidly from day 18-20 like that even with small work involving in more moments. Post 24 day like that I'm feeling dizzy if I stand more , if I sit few min I'm ok . I don't have PMS symptoms which usually I experience few days before my period .With these changes I thought I am pregnant. Today is my 29th day and in early morning I had sharp pain in left stomach and groin and got my period . First I saw some clot sort of . I even got mild fever this time which usually don't happen . Is it early miscarriage? How can we avoid such ?