B2 visa: max stay can be 6 months in a row?

[Sum14]

I am currently in the US in B2 status.
Here’s the timeline of my stay:

Arrived US: May 2018
Left US: July 2018
Arrived US: August 2018
Left US: Nov 2018
Arrived US: Nov 2018

[Libra_14]

I know that someone can stay max 6 months in the US in B2 status. As the total count of the months has already reached 6 months, is it already a violation of the law? Or they mean someone can stay up to 6 months in a row?—in that case, I think I am okay.

The "general" rule is stay allowed "per visit" for 6 months. So as long as each time you are going back before expiry of your current I94, then you are fine.

Ideally, you should stay in your home country after visiting USA for the duration of more than your stay in USA for a worry-free re-entry. So for example:
Arrived US: 17 May 2018
Left US: 26 July 2018, Stayed in US for 2 months 9 days in a row
Stayed in home country for ~20 days & returned to USA - not good, should have stayed more than 2 months 9 days.
Arrived US: 15 August 2018
Left US: 10 Nov 2018, Stayed in US almost 3 months in a row
Stayed in home country for ~2 days & returned to USA - not good, should have stayed more than 3 months
Arrived US: 12 Nov 2018

You might face questions in later entries.

[Sum14]

There should be three stamps on my passport as well with the entry and expected exit dates. But I have two stamps where the first one (for May 2018 entry) shows the exit date Nov 2018 (which is same as the online 1-94 date).

The second stamp (for August 2018 entry), there is no exit date mentioned by the visa officer.

Also, I entered US from Canada by road on the third entry (Nov 2018), the visa officer didn't put any stamp on my passport (which made me pretty confused).

[Libra_14]

I think I am already in trouble. I just checked my i-94 online and it says it expired on Nov 16, 2018.

Unfortunately, I had no prior knowledge about it. There should be three stamps on my passport as well with the entry and expected exit dates. But I have two stamps where the first one (for May 17, 2018 entry) shows the exit date Nov 16, 2018 (which is same as the online 1-94 date).

The second stamp (for August 15, 2018 entry), there is no exit date mentioned by the visa officer.

Also, I entered US from Canada by road on the third entry (Nov 12, 2018), the visa officer didn't put any stamp on my passport (which made me pretty confused).

I was planning to apply for a change in status from B2 to F2 but all these happened so fast and I have no clue what to do.

I currently have a open work permit in Canada valid until Oct 30, 2020 and my husband is working in the US in F1 (STEM OPT) valid till Oct 2020. We applied for PR in Canada and expecting to hear a positive result in April, 2019. In the mean time we planned not to stay apart and it is going nowhere but to heart breaking I guess.

Any suggestion will help to gain a lil bit of confidence-- never thought of myself as a rule breaker!

I94 is online now - the stamps are fine, check your status online.

And if you've already overstayed then sorry but yes you are in trouble.