Kitten with ongoing diahhrea

I'm a new cat owner with a lovely 5month old kitten. She's a great cat except for her ongoing bowel issues. I took her to the vet two months ago after she had extreme diarrhea, was lethargic and stopped eating/drinking. The vet put her on the I/D canned food and she improved almost immediately. The vet said she just has a sensitive stomach and possibly a food allergy (her stool was tested for other things).

I've been trying to transition her off the I/D wet food to a pet store dry food. I've been slowly adding different foods to the I/D stuff she usually eats. After failing with a few foods, I finally found a food that she is sort of ok with. I now feed her just the new dry food in the morning, and then give her some of the I/D in the evening (since I have about 20 cans left). Her poop is somewhat soft and she's a bit gassy, but this is such an improvement from any other food she's tried. She's been on the new dry food for about a week now (+1 week of transitioning).  

Should I switch foods again or should I just keep giving her this food? Is it possible it's just taking her a longer time to fully adjust to it? Is it a kitten thing and could it get better as her digestive system develops? I don't want to keep switching her diet (that can't be good for her either), especially since this food is sort of working. I'm also planning to give her some pumpkin because I've heard that helps. I'm not really sure what to do anymore and would appreciate any advice. 

I'll add she has never vomited from any of the food and is totally fine and energetic on the stuff I'm feeding her now. 

Soft stool is not "normal" for kittens. Was she previously on canned-only with the I/d or was it dry and canned?

You may not want to consider this but raw food helps kitties with ongoing bowel issues. I feed my cat primal raw frozen nuggets and he has no more diarrhea/soft stool.

She was on the canned I/D. I agree it's not normal, but it's about as close to normal as this girl has been (except when she's on the I/D canned food exclusively), and at this point I'm wondering if the constant diet changes are getting to her. Since this one is by far the best so far, I'm wondering if I should stick it out and see if it gets better or try a different food (which would mean transitioning her yet again).

My original game plan was to transition her to the I/D dry food and then to a pet store food. I tried transitioning her to the I/D dry food, but she started getting runny poops almost immediately so I stopped giving her the dry I/D. She's had a better reaction to the food she's getting now than she did to the dry I/D. It is possible though that I tried to transition her too quickly to the dry I/D.

I guess I should also mention my reasons for wanting to transition her.

1) I/D is expensive

2) Foods only available at the vet are inconvenient 

3) Wet foods are inconvenient (I don't have a car and don't live very close to a vet/pet store. Buying canned food means having to go every couple of weeks and carrying the surprisingly heavy food back to my place)

I suspect that was the case for the I/d. Some cats simply do not tolerate dry food. We have about 10 in my rescue that are this way.

My suggestion would be to try the dry I/d first to see how she tolerates this. If no issues, then maybe we could suggest a dry food that is more cost effective that more closely matches the i/d.

As a side note, have you looked into ordering online? I use Chewy.com pesonally, and can even order prescription foods and it is cheaper than purchasing directly from the vet.

That's a really good point. I guess I should first figure out if she can handle dry food. I guess I'll take away the stuff I'm feeding her now and go back to the i/d. 

I checked out the Chewy.com website. I live in Canada and they only ship to the US, but I'll see if we have something similar because that would make my life a lot easier.

Thank you for your help!