Life is ALWAYS changing, you will do GREAT!!!!!!! Breath
Now when it comes to your sewing supplies, you can start by sorting out your tools. We all have tools that we don't like (it sounded great, but after we paid for it and got it home we don't like it, can't use it, etc....), these items can go into the garage sale box.
Then move onto your threads and embellishments, sort out the small amounts and the "What did I get that for" things. These will go into 2 boxes, the first to be used up ASAP the other to be garage sale stuff (someone else will "Know what to do with it").
When it comes to your fabric you will need to go into your stash with an open mind. My stuff is in space bags and in clear totes.
SPACE BAGS:backing fabric or large cuts of something special (these are all large amounts of yardage) - is washed (I always pre-wash my fabric) - folded and the size is put on a top of that fabric (I also have a list with what the fabric size is on a master sheet that goes on top of everything in a bag (put in just before I suck the air out).
I also had fabrics with patterns to make different quilt tops, we lived in a place that I used to go down to the club house a lot to cut out or sandwich my quilts. So I made it a point to make up my own quilt kits (I would go down once or twice a week and cut out my new kit), then place each item into it's own zip lock bag (I used all different sizes bags for this, because you have small cuts or large cuts or even large amounts of a cut). All the bags and the pattern go into the large 1 or 2 gallon sized zip bag, and a note is in with the pattern on if I have backing and batting for this pattern. I divided these bags up into sizes and kinds (lap quilts, baby quilts, etc - then I stored all like in the same place). Lap quilts have a space bag and that's all that I have in this bag, the same goes for baby quilts. My queen and king sized quilts go into a clear tote.
In the living room we have a built in desk (with draws and some overhead cupboards). This is my sewing space in the 5th wheel. I had room to place pegboard on one side under my desk (it's out of the way - I do have to use a flash light - but it works), up top in the sewing area I used the mag strips for kitchens to hold up all metal items (again placed on one side out of the way).
Clear plastic totes went into the underbelly in ONE storage area (this was one that was easy for me to get in and out of. It has a slide in it, so it makes moving things around very easy. My full sized ironing board fits onto of my totes, so does my small ironing table. I always keep my iron in the first tote on top, so when I pull out my ironing surface I can also pull out my iron.
My machines are always in the inside of the house (I didn't like the idea of having them in the underbelly). My small machines fit under my bed with my space bags (I can lift the foot of the bed and have all items at my finger tips). My larger machine stays in the living room all the time.
You will find that you don't have all the stuff you had before, but you also wont miss it. When you first move in, you will think that you have to have stuff for WINTER, but you will find that you don't need all the cold gear. Because you are not in the cold all winter. I have two sweaters and a jacket, but no big coats. I didn't need all the winter shoes (they take up a lot of room too). I have one winter outfit for DH and myself and I placed them into a clear tote and they spend most of the time (99.99%), in the underbelly.
Living small, you will live differently. But you will be able to do the same things. And you will enjoy it too.