Emily

I feel for you. I was extremely articulate before the surgery, so much so that "normal" people seemed to me to be slow and plodding in their speech. Three months of speech therapy was a good start, but are you still doing the speech exercises and word lists at home? A few refresher sessions with a good speech therapist really works wonders.
Still, there are limits on what a butchered tongue can do. My surgeon & my prosthodontist both tell me that there will be zero "muscle growth" on my tongue since the wrist flap skin transplant had no muscle and they had to cut out the muscular base of tongue to get rid of my cancer. But with practice my speech has gotten better for person to person. I am still very very hard to understand on the phone and cannot get any voice recognition prompts on automated systems to work.

Because I am so self conscious that I sound like I had a brain damaging stroke or else was born "special", I do make it a point to say upfront: [quote]They cut out part of my tongue and made me a new one: but it does not work as well as the Original Manufacturer's Equipment. [/quote] That usually elicts a laugh but no further questions due to the ick factor of the mental image in the listener's mind of a tongue being cut out plus the indirect reference to God balancing it out.
I found it helps people then listen to the content of what I am saying rather than get distracted by how I am saying it.

I agree with everyone that just tincture of time and continual speaking will improve your speech.
Keep the Faith
Charm