submitting a form through node as if connected to a site - node.js

Question

I'm trying to create an automated tool that will submit a form so that it can detect changes in the response over time.
Normally, to submit this form I log in to a site and submit the form.
When trying to send the exact same request through Postman or a small node app I made, I get status 302 (while resending the request through firefox debugger works fine).
I even tried to use the HAR exported from the browser.
this is the code I use:
request({
har:{
"bodySize": 320,
"method": "POST",
"url": "https://***.com/url-to-send-the-form",
"httpVersion": "HTTP/2.0",
"headers": [
{
"name": "Host",
"value": "www.***.com"
},
{
"name": "User-Agent",
"value": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0"
},
{
"name": "Accept",
"value": "*/*"
},
{
"name": "Accept-Language",
"value": "en-US,en;q=0.5"
},
{
"name": "Accept-Encoding",
"value": "gzip, deflate, br"
},
{
"name": "Referer",
"value": "https://***.com/page-where-the-form-is/"
},
{
"name": "Content-Type",
"value": "application/x-www-form-urlencoded; charset=UTF-8"
},
{
"name": "X-Requested-With",
"value": "XMLHttpRequest"
},
{
"name": "Content-Length",
"value": "320"
},
{
"name": "Cookie",
"value": "visid_incap_1156372=***; _pk_id.7.32fa=***; _pk_ref.7.32fa=***; ASP.NET_SessionId=***; __RequestVerificationToken=***; BIGipServerMFT-Frontends=***; incap_ses_1051_1156372=***; _pk_ses.7.32fa=***; windID_1b5aa482-1126-4c17-a65f-dbac1e05cfb9=***; .AspNet.ApplicationCookie=***; family_Composition=***"
},
{
"name": "Connection",
"value": "keep-alive"
}
],
"cookies": [
{
"name": "visid_incap_1156372",
"value": "***"
},
{
"name": "_pk_id.7.32fa",
"value": "***"
},
{
"name": "_pk_ref.7.32fa",
"value": "***"
},
{
"name": "ASP.NET_SessionId",
"value": "***"
},
{
"name": "__RequestVerificationToken",
"value": "***"
},
{
"name": "BIGipServerMFT-Frontends",
"value": "***"
},
{
"name": "incap_ses_1051_1156372",
"value": "***"
},
{
"name": "_pk_ses.7.32fa",
"value": "***"
},
{
"name": "windID_1b5aa482-1126-4c17-a65f-dbac1e05cfb9",
"value": "***"
},
{
"name": ".AspNet.ApplicationCookie",
"value": "***"
},
{
"name": "family_Composition",
"value": "***"
}
],
"queryString": [],
"headersSize": 1717,
"postData": {
"mimeType": "application/x-www-form-urlencoded",
"params": [
{
"name": "key",
"value": "{val}"
}
],
"text": "key=val-url-encoded"
}
}
}, function (error, response, body) {
console.log(response.statusCode);//returns 302
});
Help will be very much appreciated