Am I unhealthy ?

Hi everyone.
I live in England and come originally from Germany. Over the Xmas periode I had family across which I have t seen for a while. They were shocked to see me that thin. I was always thin and could always eat as much as I liked but apparently I lost some more weight without realising. I am 173 cm and weigh 53 kg. I feel fine, eat healthy and more than my husband, don't exercise much(just every once in a while). The only thing I realised was that I an more prone to have asthma attacks when I weigh too little. But my mam kicked off. It's unhealthy she said and the reason why I get I'll all the time. I have two small kids which keep me on my toes but that was no excuse for her.
So my question: is it really that unhealthy and the cause for my asthma and if yes what should I do? I always add high energy food to my diet but I just can't keep it up let alone gain weight. Or am I fine and my mam just an over concerned mum ??? Tweet