That‘s exactly the point. The reactions you are describing are really common, but for the most people it comes from stress or panic. The feeling of numbness as such also can be stresfull. I used to have the same feeling when gegting LA up to a point I started to state LA in the allergy section at any doctor I went to. Two years ago I went through desensitization with my dentist which basically means many appointment of doing minor dental stuff that you don‘t necessarily need in order to get used to treatment. I had two appointments that were just about getting an injection (and a lot of talking and explaining beforehand, afterwards and during that) and being able to cope. From the second apt on I haven‘t had any reaction and one appointment later I was able to have LA for an emergency appointment without problem.
There are still things like other techniques, allergy tests etc., but having a dentist who believes you and is supportive is the most helpful thing I would say. Allowing you to get a break, a glas of water, sitting upright for a while or even stand up and get out of the surgery, if that would help, is what comes to my mind. So if your decision is to get through it today without any adjustments in the actual anesthetic or the device used, then I just hope you have a kind caring dental team that knows you have this reactions and is ready to make sure you feel better and stabilised before any procedure gets started.
Hope all goes well today, keep us posted.