Advise please feel like I'm going crazy...!!!

I'm currently 13 DPO but 15 days past my HCG injection I was monitoring my process n got negative on the 21st April so waited till the 28th n got a slight faint line on the strip which slowly got a bit darker.. So yday n today did clearblue n it sed I was pregnant... But then I don't understand why the strips ain't got darker... N my period is due on Wednesday but been getting on n off cramps like I'm about so start and feeling a bit wet I'm so confused it's driving me crazy please help.... I'm losing sleep over this...!!!!