May Allah make this difficult time easy for you and bless you with a baby soon, Ameen!
I agree with the suggestion to see a fertility specialist, as they would be in the best position to advise you. Also if your periods are all over the place, you might to start charting or monitoring, to ensure first that you are ovulating and second to determine when you are ovulating to increase your chances. Insha Allah everything is okay and there is no problem, sometimes these things just take time!! I know its easier said than done, but try not to stress too much hugs
Here are some articles with baby-making tips, maybe they will help. Above increase in your dua and istaghfar
fertility tips, how to get pregnant, getting pregnant, conception tips, ovulation, pregnancy test
Tips on Getting Pregnant
Tips to Help You Get Pregnant | Ovulation Calculator
Trying to Conceive - Helpful tips for getting pregnant