Some quick points about all that (mainly for those who read that parsha):
Bilam emphasizes to Balak that he can say only what God puts into his mouth. From that we would assume that the wording Bilam uses for the various blessings he gives are all from God. However, that is not necessarily the case. In general, we understand that each prophet is given a vision by God and then he or she translates that vision into their own words. The only exception to that being Moshe Rabbeinu for at least most of the Torah (one can argue about D'varim—and maybe we will once we get there!).
Maimonides spells out this notion in the Mishneh Torah, Hilchot Y'sodei Hatorah Chapter 7:
רמב"ם הלכות יסודי התורה פרק ז הלכה ג הדברים שמודיעים לנביא במראה הנבואה דרך משל מודיעין לו ומיד יחקק בלבו פתרון המשל במראה הנבואה וידע מה הוא...
Maimonides Laws of the Foundations of the Torah, Chapter 7 Halacha 3
Those things which are made known to the prophet by way of prophetic vision are shown to him as an allegory (mashal) and immediately the understanding (of that allegory) is ingrained onto his heart through the prophetic vision and he knows what it is.
Now you may insist that Bilam's case was different, that he himself says explicitly that he can only say what God tells him to say—maybe so. But I will point out that another prophet, Michayahu ben Yimlah, makes essentially the same declaration and yet one could understand from his words that he was also given a vision and then chose to describe it in his own way.
The context there is when King Ahab of the northern kingdom of Israel and King Yehoshafat of the southern kingdom of Yehuda make a pact to fight together to take Ramot Gilad. Yehoshafat is unimpressed with the prophets recruited by Ahab to advise them about their chances in the pending battle. He wants to hear from a real prophet of God and asks if there's one available. Ahab reluctantly admits that there is one, Michayahu, but he doesn't like him as he always predicts bad stuff. Yehoshafat insists so a messenger is sent to find him.
When the messenger finds Michayahu, he tells him that all other prophets said that Ahab and Yehoshafat will do well in battle and that he should follow suit. Michayahu replies:
מלכים א פרק כב (יד) וַיֹּאמֶר מִיכָיְהוּ חַי יְקֹוָק כִּי אֶת אֲשֶׁר יֹאמַר יְקֹוָק אֵלַי אֹתוֹ אֲדַבֵּר:
Kings I Chapter 22 (14) And Michayahu said, “As God lives, that which God says to me is what I will speak.”
He goes on to describe a vision of God asking his angels who would go and seduce Ahab so that he can be killed on the battlefield. One angel replies that he can do the job by becoming a false spirit in the mouths of the prophets who will convince Ahab that he will win.
Take a few minutes and read the whole story there—it makes for great entertainment in my book!
In any event, though, one would come away with the idea that Michayahu's vision is described in his own words despite his statement that he would speak that which God told him. So, too, we could understand that Bilam's words were actually his own. I think you can see other hints to that in the text, as well. Just something to consider.