I know dogs that have hemp treats to calm them down. For cat owners I think the only thing that's comparable to that is either catnip or pheromone spray. I definitely would look in to things that can help your kitty relax. I have this carrier:
https://www.amazon.com/dp/B00QHC01C2/ref=cm_sw_r_cp_apa_i_Jc1cFbSAH802E
I like that it has an opening from the top and bottom, there's enough room and it's a bit softer that those hard plastic ones (which my cat has definitely managed to wiggle herself out of before). This one is fully secured on all sides and the mesh is durable; haven't seen mine destroy it yet with her claws.
Tiring out your cat might work too! You can initiate in some rigorous playtime before your trip so getting her in the carrier won't be such a fuss. Some playtime, and a relaxer (like catnip if that helps her, or pheromone spray, or a visit to the doctor for a prescription) should get your cat to keep calm for a little while. I'm not sure if you take your cat on walks but during your break time you can walk the cat around for a bit, let her stretch her legs and take a potty break. There are collapsible bowls that can be attached to your carrier as well for food and water. It also helped my cat when we covered her carrier with a blanket. By covering all but one side we minimized her seeing everything all at once, and just simply talking to her.
Hope this helps!
I have three cats and I've had both types. and I prefer the soft one's with a shoulder strap. but I live in NYC and I walk about a 1/2 mile to the Vets.
Getting a cat that dosent want to get into the carrier is much easier with the top door and I'll assume that holds true with a gaggle of kittens
My girl who at one point was 14lbs doesn't like being outside and is constantly moving around even with a towel over the carrier. the soft one is soo much easier whith her moving around. also living in an apt storage space is limited so the soft ones, wins hands down
Note: that's an excellent price on the Sherpa I have Two Amazon basic ones which are great but the Sherpa looks even better, so I'll be picking that one up next week
i'll have the measure when I get home - I would guess no higher than 7-8 inches
For the carrier - as this is a one-and-done trip, we got the Large Amazon Basics Carrier
Amazon Basics Soft-Sided Mesh Pet Travel Carrier, Large (20 x 10 x 11 Inches), Black https://www.amazon.com/dp/B00QHC01C2/ref=cm_sw_r_apan_i_9H5BF4ZJ6K1H65D5FD3J?_encoding=UTF8&psc=1
Not iggy specific obviously but this worked for my friend with her 11lb iggy. Maybe buy and return if it doesn’t work.
Amazon has a pretty good one in its basics lineup. I ordered two for my cats and it was comparable to a much more expensive branded one. They've also held up very well.
I don't have a backpack carrier, but I have one like this: https://www.amazon.com/AmazonBasics-Black-Soft-Sided-Pet-Carrier/dp/B00QHC01C2/
The shoulder strap is long enough that I can wear it crossbody and it works for my guys (10lb and 16lb).
I had the Sherpa and it is pretty secure, if not a little difficult to carry with it being all square and where they put their straps. It is a pretty good basic carrier, though if you're in Canada, I would recommend the Amazon Basic Carrier due to how expensive the Sherpa one is in comparison. In the US they are basically the same price, so I got the Delta Sherpa as I fly on Delta. I would not spend double the money on it.
As for sleepypod, over sherpa, the sleepypod really is a better carrier in terms of quality. The materials are nice and it has a more intuitive design. However, I picked the sherpa because of the cost of the sleepypod was too much for something I was only using occasionally (my dog also outgrew hers by 6 months due to having stupid long legs). I would say the sleepypod is probably not worth it unless you are putting your dog in it every day, especially as you are in Canada.
Another product that may work as an intermediate between the basic sherpa and the rolls royce sleepypod is a sturdibag. They have a nicer design and a little better quality without being too expensive. My dog was also much more comfortable in it thanks to the domed design. I will caution, I was unable to get on a plane with my sturdibag because it just looks larger than a sherpa bag but I also have the xl and an xl dog...