What are my chances of having a miscarriage at 11 weeks?

I am 32 and have graves disease (severe overactive thyroid with nodules). I was diagnosed 5 and a half years ago and have been taking daily tablets of PTU since then until now. After my levels returned to normal i fell pregnant with my 3rd child. The pregnancy went well until i went into labour at 30 weeks, thankfully they stopped my labor with medications but they had to keep a close eye on me. All the way through i kept having Blood tests to check my levels. Since then i have had a 4th child and my pregnancy went well with no complications due to my thyroid.Because my levels have been steady for the past 5 years even through pregnancies my endocrynoligest told me to stop taking my PTU in January this year. I am again pregnant now (8 weeks) and although i feel o.k i'm still panicing that by not being on my PTU that my baby could be a risk. I last had bloods taken 3 weeks ago and my levels were fine. After your baby is born make sure the Dr's do a blood test on your baby to make sure that it's thyroid is not overactive, because this condition can p through the placenta. With my last 3 pregnancies i have had early pregnancy spotting so i'm not sure if it was throid related or not but i have had 4 relavently healthy pregnancies and hopefully this one will be too. I go to my OBGYN in 9 days for the first time during this pregnancy so i don't know if he will put me back on my PTU or just have me get bloods done every 5 weeks (thats how long it takes for your levels to change). Good luck and have faith that you have heard your babys heart beat twice already, i'm sure everything will work out fine.