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Actually your lithium level is fine. The therapeutic range is generally considered 0.7 to 1.2 ng/dl.
In fact, research studies have shown that people with Bipolar 1 should have a level greater than 0.7, because at levels lower, there is greater chance for relapse.

Above 1.2, is when "toxic" symptoms begin to emerge such as severe nausea, vomiting, confusion, tripping over yourself. Most research shows that these side effects do NOT happen below levels of 1.2.

Of course everyone is different. Some people can even have levels higher than 1.5 and have no problems.
But if you were experiencing "toxicity" you would be really sick. Vomiting, confusion, sick stomach. You would not be able to function real well and would wind up in the doctor.

Since you just started, I would give it time. When I started on lithium, I had several symptoms that disappeared over time. I mostly remember fatigue and a tremor. I used to have a level of 0.9 for many years, but now I usually have a level of 1.1.

Drink plenty of water and stay hydrated. If you start to notice more symptoms, I would call your doctor. But you are not experiencing toxicity.