If its been 5months you dint have periods and you say you feel you are pregnant then dear your abdomen itself will tell u.If it appears big with a lump in lower part, it suggests you have a baby within. Get an ultrasound
, it will show you what it is.
Its not possible to be pregnant with no tests positive as yet. So i suggest you get an ultrasound abdomen which will rule out other problems with ammenorhea (no periods)
As you havent mentioned your age, im not listing you other causes which can lead to no periods.
Better see a gynecologist personally, she will examine and let you know what it is and how to approach after she examines you.