Hello drgd,
We understand you're encountering an issue with swipe typing adding additional apostrophes on to words, even with you being cautious while typing. We always want your keyboard to function without issues while typing, so we're more than happy to see how we can assist.
To begin, are you referring to the "Slide to Type" feature on your iPhone, or are you using a third-party keyboard app, by chance?
If you're referring to the built-in keyboard in iOS, try navigating to Settings > General > Keyboard, and disable "Slide to Type" momentarily. Restart your iPhone, and from there, navigate back to that menu, and enable "Slide to Type" once more to see if the issue occurs. This article can help with restarting, as the steps vary, based on your model:
Restart your iPhone
Also, as a best practice, be sure that your iPhone is backed up, and running the latest iOS version, using these steps (starting with the "Before you update" section):
Update your iPhone
The following article also provides some general information, regarding your keyboard settings:
About the keyboards settings on your iPhone
Should the issue persist after reviewing the following articles, you can attempt resetting your keyboard dictionary. Please note that this will remove any specific settings you may have set for text replacement, so it's important to create a backup prior to this. Once your device is backed up, navigate to Settings > General > Reset > Reset Keyboard Dictionary.
We're confident that these steps should resolve the issue you're experiencing.
Cheers!