HCG 5 @ 13 DPO

Norma
Had faint positives a 13 DPO and had a beta done. Nurse said it was negative because it was 5. 15 DPO today and tests are getting darker, still no period. Cramps since the day I ovulated. Had spotting from 8 - 10 DPO. Any chance it was too early to get a beta? Help!