Period stopped...?

I switched birth control pills in May to a lower dose of estrogen. In June I had a very very light period (barely) for a day and I haven't had a period since.

I took a couple pregnancy tests at home that day "not pregnant" and I feel normal, but strange that it's been over 3 months since my period.

I read that changing hormonal contraceptives can mess with your cycle, but it's strange that it has gone away completely.

I have an appointment with my doc but they couldn't check me out until another 1.5 months from now since I am not pregnant....

Anyone experienced this before? Is this normal?