Ttc getting me down

Had my mirena out beginning of july periods came back after 35 days or so been peeing on opk been charting my temps for the last 6 weeks taking the folic acid gave up smoking and still nothing each month me and my partner are devastated its not happened then im depressed for a week beat myself up over having a tefmination 7 years ago as if its some kind of karma its slowly driving me insane really wondering if its worth the torture or to just give up we already have 3 kids 13,9,8 so should i just be happy with my lot x