There’s that phrase you see everywhere that says “do what you love and you’ll never work a day in your life”. What that fails to tell you, though, is that doing what you love as a job (earning a living from it) rather than doing it as a hobby changes your relationship with that thing that you love.
One of the nice things about hobbies is that you can do them (or not) when you want to. There are no pressures, expectations, or deadlines, just fun. It is something you do to relax.
When your hobby becomes a job, it now is something you have to do to pay your bills. The stakes are higher. There is more pressure to get things done and do them well. There are other motivations besides fun, leisure, or personal fulfillment at play.
Doing what you love as a job is way better than spending 40hrs (or more) a week doing something you hate, don’t get me wrong. As someone who’s work and hobbies very much overlap, I feel very fortunate to do what I love as my job. However, it is a different dynamic from when I just sewed and made clothes as a hobby.
For some, turning their hobby into a job is the best decision they ever made. For others, it takes away from the enjoyment of the thing. Before turning your fashion hobby into your job, consider how your perspective and commitment to that hobby will have to change. Is it a change you want or would you find more fulfillment in keeping a job in a separate industry and devoting your free time to the hobby instead?