Level 10 Warlock/Barbarian build

Ok, so I have been playing a human warlock/barbarian since my campaign started at level 2. (I rolled well enough that I was able to multiclass right away) Due to the summer coming to an end our DM decided it would be more fun to end at higher levels so we made a massive leap from level 6 to level 10. I figured out the levels up until level 9 but now am conflicted about where to put the 10th level.

My character is currently sitting at lvl 1 barbarian and lvl 5 warlock (pact of the blade). I intend to get to lvl 3 barbarian and lvl 6 warlock for sure with this level up. I don’t know if it would be better to take the 4th barbarian level to get an ability score increase (no feats stand out to me) or to get 7th warlock level to get 4th level spells and a new invocation. What do you all think?

My stats are (and yes my DM hates me for them but witnessed the rolls himself

Str: 20

Dex: 16

Con: 16

Int: 14

Wis: 14

Cha: 18

Feats: Tough

HP: 81 (at lvl 6)

Character wise she has made a pact with a devil and has just recently traded her soul to him in exchange for her husbands soul which her patron had obtained. I will be taking the path of the zealot for the barbarian path as it fits her patron’s intention for her to be a powerful member of his army in the nine hells.