Wa'alaikumsalam sis, rasa mengah dalam first trimester memang common sebab hormon progesterone naik dan mempengaruhi breathing pattern, tapi kalau it's affecting you sangat-sangat ni better check with your doctor or midwife just to be safe, especially since you're first-time mom dan takut benda yang tak perlu. A few of my mum friends also experienced this around 10 weeks and it settled down after a few weeks, tapi better get it checked lah sebab setiap pregnancy lain-lain, and you'll feel more at ease once doctor confirm semua okay! Take care of yourself, rest when you can, and don't worry too much, pregnancy boleh buat kita rasa aneh-aneh kat first trimester.