I really don't want to buy the bigger one!
I think if you decide this for certain then you just go ahead with the plan to stop using it. Changing things for sleep time is almost always about if the parent can stick it out to get through the tricky time of transition. I know the pod is a sort of snuggley positioner and I am not surprised she finds it comfortable. I'd choose either buy a bigger one or stick to your guns and wean it but don't go half way where you give yourself grief and give LO a very frustrating time only to then give in and put her back in it - this is unfair on both of you because you both lose sleep, both get upset and make no progress with the transition.
I can't comment on whether the pod is safe or not, my understanding is that following SIDS guidance nothing should be in the cot with baby, but I also realise there are some products which are safe.
When I moved my DS from hammock to cot it was hell, I won't lie! He had rolled in his hammock so it was no longer safe to sleep there, his cot on the other hand felt different (not snuggly at all, esp compared to hammock) and was in a different position so everything looked different. I knew I could not return him to the hammock due to safety so without any option ploughed ahead. DS was not at all happy but I stayed with him supporting him and eventually he slept. It was all over and done with in 3 nights and he was back to falling to sleep happily and independently.
I would call in day-time back up if you have any family/friend who can help you. They take care of LO during A time whilst you try to rest or nap, you take over again for nap time to put her down (I know you said nap time she was ok but you putting her down for nap reinforces the habit so you are building confidence ready for night time). Leave the housework for 3 days (or ask the family/friend to help with priority things, they can do a few bits whilst you put baby down for nap) and use every minute to either rest yourself or sooth and reassure your baby. She will adapt, she really will. You can catch up with all the house stuff etc after you are safely through the other side of this transition.
Good luck.
