Missed period with miner cramps and bad back pain and on and off again headaches

I tested yesterday and it couldn’t be anymore negative

I have low b-12 and always have I just can’t bring it up no matter what I try

I haven’t missed a period since I was 16( I’m now 20)I could go 6 months with our getting it.... I’m worried tho coz I want to try for a baby

I’ve been off birth control now for about 5 months and since been off it had my period on time till now