Hi, Thanks for the query. I understand your concern. You had undergone 4 live births , abortions twice with plan B pills & medical abortions. You had been on shots for contraception... all of these been loading with high dose hormones( leading ? hormonal imbalance ) through out your child bearing age. I feel that s the cause of your irregular periods. Any way, you nar still not 30.. so you should get investigated for the irregular menses ( CBC to detect anemia/ USG scan to see for ovarian cyst, PCOD or uterine fibroid/ Thyroid function tests / Hormonal assay ).. to find possible cause & exclude others. Get specific treatment from a gynecologist for regulating your periods. Well , after periods are regular & ovulating, you can very well plan for your 6th pregnancy if you wish so. Thanks.