Is this supposed to happen?

I am 3 weeks 4 days am I supposed to be having lower back aches this much? It's been like almost a week. It's not unbearable but it's painful and it sometimes feels like my lower abdomen hurts a bit to then stops. Again not unbearable pain though. My lower back keeps paining mainly when I sit. It's this supposed to happen or am I miscarrying?

No discharge or bleeding either. Tested this morning it remained positive but was a bit lighter (second urine)