Persist Data in TextFormFields between pages - flutter

Question

I am new-ish to flutter and I have come across a problem and I would really appreciate your help.
I have two separate forms on two different screens. Clicking the "Next" button on the first page validates the form and pushes to the second page using Navigator.push(). And all works fine until I come back to the first page using the arrow on the top left corner in the app bar which is automatically created. The data inside the TextFormFields on the first page is still filled out which is good but when I click next (which validates and pushes to the second page using Navigator.push) and go to the second page all the data inside the TextFormFields has disappeared.
My intention is to have the user data entered in the TextFormFields of both forms persistent after Navigating back and forth through different screens.
I have already looked at this stackoverflow page but the solution there did not fix my issue.
I looked into shared_preferences but the people on the Flutter discord suggested not to use it.
Here is the code:
First Page
Second Page
(I used PasteUbuntu for the code as it was a bit too long so I didn't want to copy it in this post)
This is the definition for my formField() function:
class formField extends StatelessWidget {
Function validator;
Function onSaved;
String fieldTitle;
String hintText;
TextEditingController textController;
TextInputType keyboardStyle;
formField(
{this.onSaved,
this.validator,
this.fieldTitle,
this.hintText,
this.textController,
this.keyboardStyle});
#override
Widget build(BuildContext context) {
return Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RichText(
textAlign: TextAlign.left,
text: TextSpan(
text: fieldTitle,
style: GoogleFonts.questrial(
fontSize: 16,
color: Colors.black,
fontWeight: FontWeight.w500,
)),
),
SizedBox(height: 10),
Container(
width: 335,
height: 50,
child: Material(
elevation: 5.0,
borderRadius: BorderRadius.circular(10.0),
child: TextFormField(
validator: validator,
onSaved: onSaved,
textAlignVertical: TextAlignVertical.bottom,
textCapitalization: TextCapitalization.sentences,
keyboardType: keyboardStyle,
controller: textController,
decoration: InputDecoration(
filled: true,
fillColor: Color(0xFFF0F0F0),
enabledBorder: OutlineInputBorder(
borderRadius: BorderRadius.circular(10),
borderSide: BorderSide(color: Color(0xFFE8E8E8))),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(color: Color(0xFFE8E8E8)),
borderRadius: BorderRadius.circular(8.0),
),
hintText: hintText,
hintStyle:
GoogleFonts.inter(color: Color(0xFFBDBDBD), fontSize: 16),
),
style: GoogleFonts.inter(color: Colors.black, fontSize: 16),
),
),
),
],
);
}
}