Nell as a rule of thumb if it's too uncomfortable for you then so it is for your baby. If you are sleeping thru and not being woken due to being hot I think you can rest easy that your little one is just fine.

It is a sustained temperature that we need to worry about - if something really affects your baby in the first trimester usually the pregnancy doesn't continue.

I understand completely your fears but I really believe that you can push them aside and feel quite confident that all is well...