Get the Month and Year X number of months from now - flutter

Question

I am attempting to generate a PageView that will display the Month and Year related to the number of times you swipe in either directon.
Example 1:
I swipe right twice, so I get Feb 2021
Example 2:
I swipe left 12 times, so I get April 2020
I have attempted to create a DateTime.now() and subtract an integer of months, but I'm not having much luck. I have looked at various plugins like DateUtils, but again no luck.
I have been at what should be a simple solution for while now and would appreciate a guidance.
The closet I get is the following which requires me to know the days in each month which isn't ideal
(DateTime.now().subtract(Duration(days: 90)).toString())

Answer 1

From DataTime docunamtion:
Returns a new [DateTime] instance with [duration] added to [this].
var today = DateTime.now();
var fiftyDaysFromNow = today.add(const Duration(days: 50));
// adds 1 days
DateTime _future = DateTime.now().add(const Duration(days: 1));
//substracts 1 day
DateTime _tomorrow2 = DateTime.now().subtract(const Duration(days: 1));
Also this, credit ,define the base time, let us say:
var date = new DateTime(2018, 1, 13);
Now, you want the new date:
var newDate = new DateTime(date.year, date.month - 1, date.day);
And you will get
2017-12-13

Answer 2

Y'all are going about it wrong. Presuming 24 hours in a day, or 30 days in a month, is just wrong. Here's how to always get midnight the first of the month, 7 months before today:
void main() {
var n = DateTime.now();
print(DateTime(n.year, n.month - 7, 1));
}
Just use DateTime constructors. They wrap around just fine. Works at month's end as well:
void main() {
var n = DateTime(2021, 2, 28);
print(DateTime(n.year, n.month, n.day + 1));
n = DateTime(2020, 2, 28);
print(DateTime(n.year, n.month, n.day + 1));
}
Which correctly shows 3/1 for 2021, and 2/29 for 2020, as it was a leap year.
Stop adding 24-hour days! I've got a video that explains why.... https://www.youtube.com/watch?v=usFSVUEadyo
And here's a video that goes into this with more detail: Proper Month and Day Arithmetic in Dart and Flutter: youtu.be/LpoBYgzKVwU