Hi there.
Just wanted to prop up someone else who is experiencing a randomly difficult dog!
I feel for you. Ours is now 2 and has been the most difficult dog ever.
Won't go on (I could bore you to tears) but just a quick idea about the night time toilet trouble.
I would try containing her a bit more overnight-at least then you won't ruin your rugs. We always contain our dog at night - I just don't trust her not to get up to mischief. ( she has the area under the stairs with an open bar gate on the front- her bed, some safe toys and a bowl of water). We did this from day one and when she was having accidents-She too took ages to toilet train- she could at least get away from her bed and do it, but not all over the place. I'm not a lover of cages but this relatively spacious area is a good compromise and she doesn't mind it at all. She never gets contained in the day but she's quite happy to get in her little den with a bedtime biscuit at night. I think she feels she can relax and doesn't have to patrol the house in there.
Our dog always goes out for last wee at 10pm..later if we're up late. I just think if I'm getting up anyway she might as well go out. Last night we were up til midnight, so she went out then, and happily laid in her bed til quarter to nine this morning!!!. (She's usually out by 7). 8pm is quite early for last chance, and also, if she's able to get up and move about a lot that will stimulate her to go. I bet the overnight poos are actually done in the morning.
Ours had her first season just after 1 yr old and did have a few wees indoors prior to that (she was also very sick the day before), so it is possible yours is connected to her season.
Like you, I have been shocked at how different dogs can be. Our other spaniel was so easy in comparison. This one has an opinion on everything-nothing is simple! I suppose they are like people- no two the same.
I reckon the toilet trouble is a phase that will pass though. Realistically I don't think I felt completely confident on the house training until ours was well over 1. She is fine now though-no problems.
I have a general theory on our dog- I think she is very immature. She still displays a lot of behaviour where if you said she was 6 months old, it would look quite normal but when you say she's two it looks wrong. Maybe they are similarly slow on the uptake! Let's hope so or we're done for...
!