You are on the right track; do not worry. Both your sentences are perfectly correct and very idiomatic. The third sentence is less obvious. It sounds right at first but I don’t think such a sentence would come naturally to a French person. It looks like a portemanteau sentence (if there is such a thing), a mix of:
-je ne serais pas arrivé là, si tu etc…
et
-je ne sais plus où j’en suis.
you would be understood because “en” is a discreet word but it does sound unusual for some reason.

There are two set expressions

• en passer par (là)
• en arriver (là)

where the en can be removed in informal speech:

• passer par (là)

• arriver (là)

These set expressions (with or without en) are typically (possibly always) introduced by falloir, devoir or aller. They both figuratively refer to an uneasy deviation from the path (passer) or the destination (arriver).

On the other hand, there are these regular expressions

• passer par (là)

• arriver (là) = (y) arriver

that have no implicit connotation.

Compare:

• Comment a-t-il fait pour arriver là ? : How did he manage to reach that place ?

and

• Comment a-t-il fait pour en arriver là ? : How did he manage to get into such a situation ?

or

• Pour aller à Bora-Bora, il faut faire escale à Papeete. S’il faut passer par là, je m’arrêterai dire bonjour à un ami.

and

• Pour ne pas être condamné lourdement, il faut dénoncer tes complices. S’il faut en passer par là, je préfère me taire