It's quite usual for one to be worried in cases where a period is missed especially when the pregnancy tests done are negative. Consequently, thyroid levels may sometimes affect your menstrual cycle. When the levels are up to 3.54, they do not pose much danger though they could still result in irregular periods. Also, stress, weight changes, and hormonal imbalances can lead to this irregularity too. However, you need not worry about this stage if it stops here but should see a gynecologist if it persists.