Hi Betty,
You can do it!
Coincidentally, I've been reviewing how to pack light on websites and from memory, to practice packing for an 11-day tour (my first organized tour) this fall. So, I'm certainly not an expert, but below are some things to consider. When my husband and I traveled, I had to handle all our luggage and his chair, so I quickly became better at packing. I'm still not an extremely light packer, but it's amazing what can be painlessly left at home with a little bit of planning.
There are many websites with packing tips; it's almost a cottage industry. Google and check some of them out and find what works for your situation.
For ten days, you should be able to pack lightly enough without wearing your old ratty clothes to throw away or mailing clothes to yourself, unless you just want to, although those are options. Dark pants can easily be worn two or three times, so four should be plenty, and you might get by with three. I like to take knits, and there are some stylish ones that don't look like grandma pants. They don't weigh a lot, don't wrinkle as much as woven pants, and can be more easily hand washed and dried if it came to that (it probably won't). But any will do if you don't take the whole closet! Try to stay away from heavy ones, though. Lightweight cotton or blend tees, turtlenecks, or pullovers, along with a blouse or two, don't take much space so you can take more of them. A quilted vest, wool blend cardigan (warmer and lighter than cotton), or a jacket can be taken if needed, and can be carried instead of packed if space is tight. If weather is iffy, take a few items for layering, and maybe one of the little synthetic tank top undies for warmth. For cold weather, I have a few fleece pullovers that are almost too toasty warm, and they weigh almost nothing (got them at Landsend on sale). For most kinds of trips, the shoes you wear and a pair of flip-flops for the train shower and to use as slippers, should do. Couple of sleep tees or gowns (one if you shower at night), daily undies--or wash a few out in the shower or sink, a few bras, socks, little travel size toiletries.
Yes, I know Rick Steves would throw over half of that out, but I'm not nearly that good.
I have a hard time forcing myself to go ahead and make up my mind what I'll wear during the trip, rather than taking extra clothes so I can "decide later." Guard against that. LOL
You should be able to get most of this in a 22" case or rolling duffle if the third dimension is generous. It's always good to also take a tote bag for items you need to keep handy, valuables, meds, snacks, etc. They make some little foldable ones that are feather weight, or any cloth or nylon tote. If you check your main bag, include a change of clothes in your tote. I guess the chance your suitcase will get lost is practically nil on a train, though, so that's not as important. (But put your name and cell or hotel number in every bag.) If your rolling suitcase (God bless the person who invented those!) doesn't already have a strap for this, use a strap or belt, loop it through the rolling case's handle (not the telescoping one, the one on top of the bag) and through your hand bag's handles, and let it hitch a ride on the rolling case. Use a small purse with a shoulder or crossbody strap so it leaves your hands free for other things. Weed out the things in your purse, but take a second credit card (another thread).
The packing method that works best for me is the fold lengthwise and stack, bundle method (I learned on line, not sure what it's really called). Fold pants once lengthwise, lay them on a table, stacking and alternating the direction. One pair waist to the R, next pair waist to the L, etc., then shirts folded once lengthwise and alternate, stacking. Then carefully, without bunching, fold one end of the whole stack over, smooth and press down, then keep folding over and smoothing down, to make the size rectangle to fit in a part of your suitcase. The stack can also be rolled, but I like making a rectangle or square bundle better. i don't know why, but this method takes up much, much less space than folding or rolling each item separately. It's almost magic. If it winds up too tall, take some things off and make a second bundle. (or weed out a few) Put undies in a gallon zip baggie and press the air out, roll misc items and tuck where there's space. That's just what works for me. I have gotten a week's worth of summer clothes for the two of us in our expanded 22" rolling case this way. And I could push him in his chair with one hand while pulling our suitcase, tote attached, with the other. Do what's necessary to make it easier for you, and don't stress about getting it perfect.
Don't plan on the worst-case scenario, don't take things you "might" need but aren't likely to. In a pinch, you can always buy something at your destination, just like the locals do. You are not going to Mars.
I've read this advice in several places: Take half as many clothes and twice as much money as you think you'll need! (No, I don't always follow it.)
Sorry so wordy, but I'm into this, too, right now. Have a wonderful trip!
Edit to add: If you need help boarding or getting off the train, by all means let someone know you need help, a little ahead of time. Amtrak employees were always very helpful to my mobility limited hubby and me. It is part of their job, but they always seemed happy to do it. We did give them a tip for any extra service.