I've been trying to get the Flag Defender Pin for ages now, in one round I got about 7 - 8 flag defences and still didn't get it. Does anyone know how to get it or whether it's glitched or not

It's designated as your squad's defense point, yeah?

didn't know it has to thanks

Fuck that thing is hard to get. I swear I should have gotten it last round. Spent about 4 hours trying to get it. It sucks because in conquest I kept either being on a team that rolled through into their spawn, or had the same done to us. So fucking frustrating.
 
 
And last round, I spent the whole time parked up at A, waiting for them. I got enough flag defense kills, but dammit I didnt get the pin. That and roadkill are the only ones left for me.

This pin was a goddamn nightmare for me to get, so I feel your pain. This is how I ultimately got it:
 
1) Had a friend join me in a 0 player server (conquest naturally)
 
2) I took over alpha 
 
3) I marked alpha with a squad defend order
 
4) I left alpha, meaning I was far enough away so that I was no longer "protecting" it with my presence.
 
5) He ran up, and start taking alpha over.
 
6) I ran up before he was done, and killed him.
 
7) I would reset the flag all the back to MY ownership , then run away again
 
8) He'd run up again, I'd run up again and kill him, etc.
 
9) We did this a grand total of SIX times (it takes SIX, not four, like it says)
 
You will be getting the +30 flag defense notice each time. This has to happen six times, then you'll get the stupid pin.
 
Good luck. This was the very last pin for me, and the only one I "cheated" to get because I tried legitimately for about 5 hours before giving up in a ragequit.

SIX? Maybe that was my problem.
 
Maybe it would be easier if the orders and spotting used different cooldown timers. I find it hard enough to set orders half the time and end up getting killed while looking up at the marker 5 yards in the air.

Point at the flag you want to defend, press the 'spotting' button. This is a 'Defend' order. Successfully killing attackers in the vercinity of the flag will eventually give you the flag defender pin.

You're joking? It was easy. Sit beside the flag, tag it and kill any enemies who get in proximity of taking it.