Hello and welcome, I believe the guidance is supposed to be somewhat customised to the individual for one thing it can be different between the different types of diabetes but I believe the NHS can also give slightly more relaxed levels for those who are older or on different drugs to reduce hypo risk.(Not saying the age thing is right or wrong, just a typical NHS blanket approach at times)
For type 2 the levels suggested look reasonable and yes, your body is used to higher levels, there is a thing called a false hypo where you can feel slightly odd as your body is craving the old normal
I agree with @Andydragon that what you may be experiencing is a false hypo. For me as a type 2 on no medication I won't get a hypo so I try to keep my levels as low as possible. This is different for those on medications.
4-7 is what I aim for..
If your new to low carbing you may get all sort of funny sensations as the sugar flees your body. I had blurry eyes, odd skin sensations and more BUT as you are on medication do keep an eye on the side effects that may, or may not, come with those. Read the packets.