It sounds like you've done a great job with regular, sustained use of dilators to restore the vaginal opening. Be aware that the top of the vagina tapers a bit, so it's possible that the largest-diameter dilator, because of its width, just won't go in as far as the others. The only way to assess for certain what's happening is to have a pelvic exam with your health care provider; I'd explain to her or him that you've been using dilators and see whether s/he finds anything other than normal.
During intimacy with a partner, many women find that they can control the depth and angle of penetration more easily when they are on top. That seems to be a safer starting point for women who have reason to better understand what's most comfortable–and pleasurable.
Congratulations on taking care of yourself!
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