Bit hard to tell over the net lol especially without doing your pulse and o2 sats whilst you feel breathless. A certain amount of breathlessness is normal in pregnancy and common not to say everyone gets it as they don't. Could be the asthma playing up a bit or just normal in pregnancy. I would get your dr to listen to your heart next visit which I think is usally normal to have a full health check for your first antenatal visit although I never had this with both mine. I know the Drs I work with do though.