Can Having Sex Without The NuvaRing Cause Pregnancy?

i Have been using the nuvia ring for about7 months now but the last 2 months ia have barely bleed and during sex the ring has fallen out my husband does cum inside me everytime, i have taken a home test to see if im pregrant it showed up neither postive or negative. Last night the ring came out after sex so i left it out and then we had unprotected sex, could i be pregrant?