Missing My Period Every Other Month

Melissa
Help, I have been missing my period every other month. I went to the doctor and got blood drawn and really scared. Haven't received my results yet. This is not normal. I've always been regular for 17 years. Been of bc for 3 1/2 & of course just starting to try getting pregnant and this is happening. Has anyone experienced this before? Took test and not pregnant and I just started my period but missed Dec and Feb. I haven't been stressed, not taking any meds. Any advice would be greatly appreciated. I'm 32yo will be 33 in July. Thank you!