Loosing hope

Hi lady's I've had two miscarriages already my partner and I have been ttc since May of this year I'm starting too think it's not going too happen,my doctor said that there's no need too look into the two miscarriages as they don't start too worry till the 3rd one you have,my two lost babies were not with my partner im with now and he has two children too a past relationship,I'm really starting too think it's me.... Any advice or help anything would be really appreciative Thank You