「〜してから何ヶ月間。」は英語では "It has been XX many months since 〇〇」になります。
例えば
It has been six months since I gave birth.
It has been half a year since I gave birth.
出産してから半年間、
It has been two months since I moved to Tokyo.
東京に引っ越してから２が月です。
I recieve 200,000 yen every two months.
2ヶ月に一度20万円もらえます
「〜してから何ヶ月間」は疑問で聞いている場合には「How many months has it been since 〇〇？」になります。
例えば
How many months has it been since you had your baby?
赤ちゃんが生まれてから何ヶ月間ですか？
How many months has it been since you quit your job?
仕事をやめてから何ヶ月間ですか？
ご参考までに。
「出産してから半年間、2ヶ月に一度20万円もらえます。」 = I got 200,000 yen once every two months for half a year after giving birth.
「出産してから半年間」= it's been half a year since giving birth
アメリカ合衆国 
