A month is 4.5 weeks. That's why pregnancies are considered to be 9 months, not 10 months, at 40 weeks.
But actually, since you get two "free" weeks at the beginning of your pregnancy - i.e., when you've been pregnant for 2 weeks you're considered 4 weeks pregnant, pregnancy is only actually 38 weeks not 40.
It's really easier to count pregnancies in weeks, but if strangers ask you how many "months" you are at 9 weeks, you can say almost 2.
You are 2 months and 1 week. A month is every 4 weeks.