Wa'alaikumassalam! Sesak nafas kat awal pregnancy memang boleh jadi, especially kalau activity sikit pun terasa, tapi kena betul-betul check dengan doctor sebab tengok timing dan symptoms you're having lah. Seorang mum friend aku dulu also complained pasal ni kat 4 minggu, turned out dia anemia ja pun, so worth getting it checked out properly. Jangan worry sangat, tapi jangan delay jugak, better safe than sorry kan, especially when you're expecting.