I don't believe that the Bible points to Ellen White at all. If she truly was a prophet of God (and honestly I have some doubts about that), that would mean that she had the biblical gift of prophecy, but the Bible doesn't specifically mention her. The Bible also gives us tests to help us determine whether a prophet is true or false, and we can apply them to EGW's writings to see if she fits the biblical criteria for being a prophet (although many Adventists disagree on whether she stands the test).
Many Adventists refer to EGW's writings as the "Spirit of Prophecy," quoting from Revelation 19:10:
REV 19:10 At this I fell at his feet to worship him. But he said to me, "Do not do it! I am a fellow servant with you and with your brothers who hold to the testimony of Jesus. Worship God! For the testimony of Jesus is the spirit of prophecy." (NIV)
They also relate this to the following texts:
Rev 12:17 And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ. (KJV)
Rev 14:12 Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus. (KJV)
Many Adventists see these as directly referencing the Adventist Church and Ellen White. I personally do not believe that these texts refer to EGW or even to the Adventist Church because not all of the remnant will be Adventists, and not all Adventists will be part of the remnant. This simply addresses all true Christians who remain faithful to God at the end of time. Also, even if EGW were a true prophet, calling her "the spirit of prophecy," as if she embodied the whole of prophecy, is taking Rev. 19:10 completely out of context. The angel was telling John not to worship him because he was not the focus of the visions John was being given; Jesus was. Prophecy is given to testify about Jesus, not to glorify the messenger. That was the angel's point, not that EGW was the spirit of prophecy.
I agree with you that many Adventists place EGW's writings on an equal level with Scripture although that is not our official belief. However, many Adventists do interpret the Bible through the filter of Ellen White rather than reading it for what it actually says. All of our doctrines must be tested by the Bible, not by Ellen White.