Losing faith...ttc #2 for 1yr and a half...

I know there are lots of ladies that are ttc for much longer than me and also ladies that are still ttc there 1st baby but it affects us all in our own ways. .. i have been strong for as long as i can but i have fallen.... i can't understand why it is so much more difficult to concieve this time round... i have one little girl so i kbow that i am capable of having children so what is going wrong... i have had all my checks done and i am taking thyroid medication for the last 3 months ( is it this does the body need more time to reset?) My periods are finally back to normal i seem to be ovulating as i get the positives on the opks good strong ones i might add... we do it on all the right days.. but still nothing.... and i know don't think about, don't stress and when you least expect it, it will happen but this time round i just can't stay positive.... my morale is so low and with my husband away and not coming home this month l, plus my mum living in another country..well all my family actually as i live abroad, it just makes it so much harder. I thankgod every single day for the beautiful child he gave me and i love her so much she is the only reason i get up everyday but i long to give her a sibling... i hope it happens eventually l... sooner rather than later. Sorry for the long rant but i have no one else to talk to.