So did Louise have an abortion or not?

In the pub, Louise asks Sophie if Sophie had had an abortion.

Louise says that she once thought she was pregnant, but turned out it was a false alarm. Then the bloke left her anyway.

IMHO, it is clear that she is talking about Johnny. In particular, in the bathroom later it is clear that "babies" are a sensitive topic. (When he mentions that his mum was younger than Louise when she had him, Louise reacts as if it is a conversation they have had many times before and thinks that Johnny should no better than to go there).

I didnt think that Louise was lying to Sophie.

However, most of the other evidence was consistent with Louise having had an abortion, and that this was what had (a) caused her to split up with Johnny and (b) to feel she had to live away from Manchester.

Eg
- Johnny seemed to think that the fact that she was Catholic was important (possibly angry that she had not stuck to the letter of their law);
- She mentioned "I could have had a 4 year old kid by now." But why say that if she had never been pregnant when Johnny thought she was. If she had never been pregnant at all, then the hypothetical child could have been any age.
- She talked about being unable to return to Manchester. But whatever it was that was keeping her away seemed to be solved if she and Johnny got back together.
- The bathroom conversation mentioned above.