Hi Martina,
I can definitely understand the struggle with this. Fortunately, when I travel I usually have people with me to help. I know it can be hard to ask for help with holding things but for us its crucial ! My suggestion would be to ask for help with bringing things onto the train if you need it. There are more people willing to help you out than you think. Also, I would suggest taking a few rolling bags with you so you can pull your luggage as opposed to carrying it. They even have small pull luggage for smaller items. I get your worries though and I’ve had a hard time with this myself.