Most everything written above is very good indeed. Here is my "two cents worth"
1. It is a good idea to get used to having a loaded rucksack on your back. I use sealed plastic bags of crystal kitty litter, which my cat will ultimately use anyway. Start with one small bag. Add bags as you get used to it. I currently use one 8 pound and one 15 pound bag in my 35 liter rucksack. This is an all-in weight, including the rucksack, of 25 pounds / or 11.4 Kg. THAT is 10 percent of my naked weight.
Adding weight gets you used to having the rucksack on your back, helps you to properly adjust it, and as you add weight, you get a better idea of the strain.
2. Ultimately, you might consider actually packing your rucksack with the exact items you plan on taking on Camino. That will tell you fairly quick if you have too much crap.
I likely hold the record for mailing excess stuff to Ivar from down the road when I realize I am carrying too much. On each of my three Caminos I have sent him increasing amounts. Last year, coming off a 10-day Camino from Porto, I actually mailed him FOUR boxes. One was tourist stuff from the beginning. But THREE boxes were excess I did not need. We had a good chuckle over that. But, each year I think I learned my lesson.
Actually, I am following Albert Einstein's definition of insanity: I am repeating the same experiment year after year, in the hopes of a different outcome...
There is a ton of useful advice and suggested packing lists here on the Forum for you to use for comparison. Some of our veteran colleagues maintain blogs separately. They also post their experience-laden packing lists there for your consideration. Use them.
Finally, I use a dietary scale that weighs in kilograms and ounces that I got in Target. I weigh literally EVERY item I plan to take. I record weights in kilograms and ounces on the worksheet and the totals go up or down as I make changes. Just watching the total causes me to revisit what I think I am taking to see what and where I can shave a few kilograms. Even things that "weigh virtually nothing (LOL)" eventually conspire to weigh a kilo or more. So, worry about every kilogram or ounce. Let the worksheet run the fluid total. Make adjustments as indicated.
I also use Excel to maintain a packing list worksheet. It has formulas to accumulate all the weight, by pocket, pouch, tote bag, organizing ziplock bags of stuff, and my externally worn bag (chest load) and rucksack. Each year, I make a copy of last year's Camino packing list and refine it. EVERYTHING that I will wear, carry, or tote in a a pack is included.
This year, I am actually down to 11.8 kg, not including what I am wearing, and what goes in my cargo pockets. For me, that is a new low record. But my departure is still nearly two months away...
But planning ahead focuses me and makes me evaluate alternative choices.
I hope this helps.