I took five pregnancy tests , two negative& the rest came positive so I’m confused. I keep ringing to see my doctors but with the COVID they say there booked & very busy they’d ring me back.

my period didn’t come obviously but before I even got near my date of when my Period was due .. I felt off with cramping sore boobs , & bad lower back pain .. I got these same symptoms when I was last pregnant but sadly had a miscarriage at 6 weeks, this time around I haven’t had any spotting or blood thank god but I took the early pregnancy tests. I took one yesterday & the day previously came up positive , then today I got a negative so I’m so confused. Maybe this test I took was invalid?