I would probably say plump.
Essentially, in this question, you're looking for the word that would be the least insulting. More broadly, when asked about positive connotation, you're looking for a word that is not viewed negatively.
Words like fat and cheap have negative connotations, especially when applied to people. Words like plump and frugal are much more positive.
She felt sad because she had been looking forward to it and now the days were longer without him.
