Trying for baby #1

Me and my husband have been ttc since feb 2018. I do have some medical issues but my doctors all gave me the green light to try. However they advised against fertility treatments because the possibility of multiples is too risky to chance. It's a bit discouraging at this point. Not to mention my cycle has been so crazy. I get it every month but not always at equal intervals. Add in the fact that my 3 best friends weren't even really ttc and got pregnant all within that year. I'm starting up with opks again. Last time I tried them albeit briefly (2-3mths) I never saw a positive. I guess I'm just looking for any advice plus good vibes and prayers would also be greatly appreciated!