There are not a lot of synonyms for the verb 'end up', but here are a few:

http://www.thesaurus.com/browse/end%20up?s=t

" The last time we met I became pregnant"

"end up" =  finish

e.g.  I started the race in front but I ended up last.

When I lost my job, I ended up in debt.

I went regularly to language classes, but ended up learning very little.

The correct sentence is:

"The last time we met I ended up pregnant".

It just means that last time they met, they had sex and she became pregnant as a result of the meeting.