It's tricky, but does "last July" have to be July of the previous year? For example if you're in December 2016 and speak of "last July" would it refer to July 2016 or 2015? If it indeed always refers to last year's July, it should be accepted.
From YardenNB: “from” is usually mi but before gutturals (א ה ח ע ר) it may change to “me” but even there if you say “mi”, you won’t sound strange to most Hebrew speakers.