Ok guys, I did it. It was kinda long but in the end I succeded. Even got the marriage proporsal
If someone else meets this issue, I suggest to check the following, made by me using my experience, conditions:
1. Try not to miss any flirt options
2. Rush KotFE till chapter 9 (the cantina scene). You need to rush it to avoid any patches, because they somehow break romances in KotFE (Lana's for sure)
3. Get her influence to 10 before the cantina scene, just in case
4. Support won't really help you, if romance breaks (i tried)
5. From now on, you SHOULD NOT get your romance bugged.
Hope this helps