Not exactly true. The keto diet is a low carb, not a no carb diet. (My diet has similarities to the keto diet, for health reasons).

You are six weeks in. There will be adjustments to be made. After a few months, your body will grow in different ways, and I fully expect that your strength will return.

Also, I found that my diet has improved, and I get far more nutrients than when I first started out.

For example, I now put sliced mushrooms in the sun for 15 minutes which increases their vitamin D content by a factor of 20! (Backed by research, surprised the heck out of me)

Another example is that I eat a lot more seeds.

You still can regulate the amount of carbs you get when on the keto diet - and if you are working out, then I'd aim for more. Flaxseed, sunflower seeds, and avocados are a good source. There are others.