What vitamins should i be talking? Or other natural supplement?!?

Any vitamins or supplements i should be taking?!?! I could really use any advice or suggestions. My fiance & I have been trying to conceive for 3 1/2 yrz for baby #1 we've had 1 miscarriage a year or two back and nothing since! I'm 20yrs old my period is very very irregular but it always comes once a month! So ladies plz send some luck our way as I will for you!