15 lv character: pure fighter or barbarian multiclassing?

[4BR4]

Hi Ground,
I'm playing in an adventure that will bring the characters up to lv 15.
Right now I'm level 7 Varian Human Battlemaster Fighter with Glaive STR 19 (magic item 16 base) DEX 12 CON 16 WIS 13
I took the following feats: Polearm Master, Sentinel and Great Weapon Master and I took Tunnel Fighter as fighting style.
Going forward in the build the only feat I already planned to take is Resilient (WIS).
I'm in doubt if continue with only fighter levels or if add 3 bear totem barbarian levels to the mix (from lvs 9 to 11, from lvs 9 to 10 and then 15, or from lvs 13 to 15).
Doing the second route I will eventually take the ASI at level 8 to increase my dexterity and then move from a Plate to a HalfPlate from lv 9.
There is a good chance that I could reach STR 21 with another magic item, so I'm planning to not increase my strenght with an ASI.
I think this is all, so I'd like to recevie your opinions on how I'm planning my build.
4BR4

[da newt]

In my opinion, grab Barb 3.

W/ PAM, you already have 3 attacks/round (with a high likelyhood of OpAtt), so the additional attack at fighter 11 is only a ~25% increase. Rage's +2 damage will offset a bunch of that, Reckless is awesome, and damage resistance to almost everything is GREAT.

[4BR4]

Going Fighter 12/Barbarian 3 means two less maneuvers. Not a big issue, I'm planning to take Reposte, Precision Attack, Trip Attack, Menacing Attack, Disarming Attack, Pushing Attack and Goading Attack.