is this possible

So has anyone ever just felt pregnant like I feel like I just am pregnant but I can't get a positive pregnancy test blood work has come out positive then negative and it's been awhile and now it feels like I have movements like fluttering in my belly.has anyone went their whole pregnancy just not knowing but suspecting and get discouraged because u have negative tests ..please let me no if anyone has thought they were pregnant and end up really being pregnant.the drs have not preformed an ultrasound