What could be wrong?

My partner has a 3 year old from a previous relationship (currently going through court for joint custody) his previous pregnancy was healthy etc.

We have been TTC for a year and nothing, couple of false positives or maybe faints but period always comes!

I’m a healthy weight for my height, eat a balanced diet, maybe have to much coffee but don’t smoke or drink allot, (special occasions) partner does smoke but not excessively.. my ovulation tests always get a peak day on the dot and my periods always arrive on time, I want a baby so badly, could anyone give me some advice who have been through the same? Is there anything else that could be wrong? I have no symptoms for Endo or PCOS as my periods are regular and I only get like 1 day of cramps! Is there anything else or anything I could take to maybe help?

Please I’m desperate