Is this what you've got?
http://www.walmart.com/ip/Straight-Talk-Huawei-H881C-Ascend-Plus-Android-Prepaid-Smartphone/23573712
A very budget pre-paid Chinese phone that Walmart sells for $29.99, and it's a similar price pre-paid from China Mobile as well.
The fact is, this $30 phone just does not have much internal storage at all, 1GB in total apparently, with only 300MB usable. This thread on Android Central discusses it.
http://forums.androidcentral.com/huawei/350766-huawei-ascend-plus-straight-talk-low-memory.html
If Google Play is stating "Insufficient storage" then that's what it is. You managed to clear it once in your first post, but it's apparently filled up again.
Adding an SD card, no matter how large, will NOT fix it. Can't really do it "manually", because Google never intended that, it just doesn't have that provision.
Frankly Google intended their stuff to be running on a Nexus 6 or something, which is a $400-$500 phone that has plenty adequate internal storage. In China, budget low internal storage phones aren't so much of a problem, for one there's no Google Play, and secondly many people tend to favour small casual games, around 10MB 20MB or so. But supermarkets and pre-paid carriers like Straight Talk are selling these things with Google, and they don't really care about the user experience and what problems that may arise with them.
FYI suggest have a look at Storage Truth, that will give you an accurate indication about what you've actually got.
http://androidforums.com/threads/qu...ruth-read-me-first-now-with-ram-truth.906249/