I'm not sure what you mean about 'throwing your voice' -- do you mean that you are too loud? The good news is that (at least for me) how I practice comes right into my presentation. In other words, for me I found that I would practice at home in a quieter voice because I was worried about disturbing the entire house. Then, when I gave my presentation, I was told that I was too quiet. Yikes!
The first step is being aware of it, so you are already on your way. Perhaps the next best step is to practice, BUT focus on one thing at a time. Voice modulation is not a -- you get it or you don't thing -- it's a lot of things coming together. The best thing is -- if you learn to do this well, wow, you will amp up how you come across.
There are a few things that you can consider -- voice modulation for emphasis. If you come to a compelling point, tell it and then pause, confidently looking at your audience. Yep, let it sink in. This also works if you have been giving a strong presentation and you suddenly become quieter -- because something profound is coming, so your audience will tune into that. Quiet can communicate fear or profound insight or something else depending on how it is used, but your audience will hear it as intimacy. (Note -- being too quiet throughout your speech may come across as timidity -- too much of a good thing, you know).
If you mean that 'throwing your voice' is too aggressive / loud, you could consider speaking to the people closer to the stage (mentally) that way, your voice should naturally lower just a bit.
Overall, please do consider that if only 1 person has given you this feedback, ask around before taking on a lot of study and work. We are all operating in our own worlds and something like this CAN be subjective.
I wish you all the luck -- it takes guts to admit to needing improvement and asking for tips. Good for you!