MESSED UP CYCLE? Am I not fertile? 😰😰

I'm so depressed ... All I want is a baby in the future and my period cycle all of a sudden since August has messed up! Constant spotting... A period every other week? What could cause this ? I was regular with ovulation! Now seems everytime I wanna ovulate I bleed again! No break from bleeding this would never happen! I'm 15 .. Does this mean I won't have kids in the future :(( I'm going to start trying conceiving by the time I'm 18 so I'm worried What does This meanÂ