I’m not sure what the question is. Do you want me to fix the grammar of the sentence?
“I had 4 of the most expensive cupcakes here two days ago, and 7 yesterday.”
The rest of the grammar is correct.
If you want want me to continue the pattern of cupcakes then it’s
4, then 7, then 9, then 11 (etc)
Just add 3 each time.