Everyone is rightly commenting on the importance of good communication and I totally agree with this.
However to describe the OP as “barely literate” (as one poster did above) is as offensive as it is inaccurate. She is clearly literate and seeking support.
Comments like that are not helpful as they exaggerate the scale of the challenge and simply contribute to the OP’s crisis of confidence in this respect.
OP ignore this nonsense as it is very clear to me what you’re saying, and I understand that your messages might not be as straightforward as you would hope because you’re not sure of some of these answers yourself.
Strategic communication is about knowing your audience, knowing what you want them to do and choosing the words and messages which will help them to take the action you want them to take.
Not everyone can do that on the spur of the moment, but you can help yourself by considering who you’re more likely to fluff your words with and always have at the back of your mind how you might engage with them the next time you are in that situation. Some role playing (as cringey as it sounds) does help with this.
Likewise, if there is any form of neurodivergence at play here which means that you are prone to waffle, mix up your words or which affects your working memory or processing speed, you might want to consider making your employer aware of this.
To progress, yes the standard school of thought says that you need to be a good communicator. I would maybe challenge that slightly by saying that you need to be a good influencer and this recognises that some folk also need to be supported to communicate in the right way. It doesn’t lessen the value of their contribution or what they have to offer in senior roles.
If you can lead, direct, develop, create, add value and generally offer good skills, you will find your own optimal way of influencing and sometimes that comes from surrounding yourself with great people who ARE great communicators and will help communicate your vision.