Miscarriage, cycle change, or ...???

I've been feeling pregnant for the last month (3 weeks of tender breasts, extremely emotional, intermittent light cramps, no egg white cervical fluid), but 3 home tests all were negative. My cycle is normally 36days, but after an early bbt spike, the glow app shifted it to a 30day cycle - despite not fertile cervical fluid. I still thought I was prego, but then my period came in clots with much more cramping than usual. Is this a potential miscarriage (tho I didn't test positive), or something that happens when your cycle length changes? If I was pregnant it would have been 7 weeks. I had similar cramps and apparently a miscarriage last December after testing positive early (very faint line) and then having a ton of stress and a big scare (oven exploded in my face). Any ideas?