Since you are testing you can pick your menu...try different foods...then test a couple of hours after eating...see how your blood sugars react...we should be aiming for no more than a 1-3mmol rise two hours after eating...keep a food dairy...there is no need to starve yourself...or eat so little...you will get there...it just takes time.
I'm T1 but only diagnosed last year. I completely understand the feeling of muscle weakness. It happens because your body has got used to drawing on the sugar circulating in your blood, so by getting those sugars under control you are taking away the easy source of energy.
I'm on a trial so it's given me access to a v good consultant who has more time to answer my 100s of Qs. Basically the only way forward is to keep exercising so your metabolism adjusts. He warned me it would be at least 6 months and I'm at 5 so far and it is improving - but I'm nowhere near the energy levels I used to have.
First the good news, I have always had a little milk in the tea, and it has not stopped low carb working for me. (Just use full-fat milk if you can.)
It is likely that the crumpets or ryvita is stopping your body leaning to get energy from fat, they also increase your BG. When your BG then drops down again you can feel depressed. (The brain does not like fast dropping BG, it much rather have a constant low level.)
Try having some nice bone broth (with a little salt) or olives and cheese instead. "fat bombs" (google them) are also a very good option while your body is getting used to low carb. Most of us have found we don't lose much weight until we get BG under control, and that we then want to eat less, hence don't let any weight issues put you of having lots of "fat bombs" in the first few months.
I started low carbing at the beginning of January and my eyes went very blurry but have since gone back to normal. There's 2 dn's at my gp's and both have totally different views on low carb. Luckily I saw the enlightened one last week who was very pro low carb the previous one wanted me to eat crumpets (which I'm very fond of ) and carbs four times a day. Which got me into this mess in the first place.
Last week's dn Claire recommend this site to me but I told her I was already a member. She isn't diabetic but lost 3 stone doing the lchf so she is really pro lchf