Big cat animal companion 7th level advancement

[Nynphaiel]

Guys, I just leveled my druid to 7, and I'm struggling with my animal companion advancement.

I should go from this:
Starting Statistics: Size Medium; AC +1 natural armor; Attack bite (1d6), 2 claws (1d4); Ability Scores Str 13, Dex 17, Con 13, Int 2, Wis 15, Cha 10; Special Attacks rake (1d4); Special Qualities low-light vision, scent.

to this:
7th-Level Advancement: Size Large; AC +2 natural armor; Attack bite (1d8), 2 claws (1d6); Ability Scores Str +8, Dex ­–2, Con +4; Special Attacks grab, pounce, rake (1d6)

plus this from the animal companion table:
Class Level 7
HD 6
BAB +4
Fort +5
Ref +5
Will +2
Skills 6
Feats 3
Natural Armor Bonus +4
Str/Dex Bonus +2
Bonus Tricks 3

Besides, there is the Ability Score Increase at level 4 that adds a +1 to any ability.

My doubts are as follows:
Not pretty sure what to do with the Ability Scores from the advancement. The +8 adds to the previous STR and then I should add the +2 bonus (which means 4 more points to the AS)?
Should I then correct the AC, attack and STR due to the size change, or are all those already included in the stats?

Thanks for your help, and I'm sorry if these questions seem pretty dumb, but Pathfinder stats blocks are always giving me headaches... u.u

Cheers,
Nyn

[Rikkan]

Ability scores will be:
23 strength (13+8+2), 17 dex(17-2+2), 17 con (13+4), 2 int, 15 wis, 10 cha.

Your Armour class will be: 19: 10 -1 (size) +3 dex +7 natural armour (1+2+4) + any barding or other effects the creature benefits from

Your attack bonus will be: +9: -1 (size) +4 BAB +6 Strength

You'd still have to spent your +1 to an ability score.

[XigXag]

Getting your animal companion up to 3 intelligence is often worthwhile.

[Captain Zoom]

If you don't have barding, MW Studded Leather is both affordable and doesn't require armor proficiency to use... gets you a +3 AC and you can further enchant it.

If you've got money, mithral chain shirt barding is definitely better... +4 AC and a higher Max Dex.

[Nynphaiel]

Thank you so much, guys!!!

I'm actually going for the mithral chain shirt. Amra has became one of the party's tanks (unintentionally), so AC is a priority.