How to protect the timeline of my project when the supervisor is not willing to negotiate anything? I am currently working on an 8 month final project, of which 1 month has already passed. Its for an Engineering Doctorate degree. I have one supervisor and one client (who is a Phd student).

Situation 

It is really important for me to finish the project on time. The most important reason is that I was recently offered a job and I told them that I will join after 7 months. So if I don't complete the project on time then I might lose this job. Secondly, I am living in a foreign country (all of my colleagues are too) and earn some monthly living expenses from the university. These living expenses will stop exactly after 7 months. So if someone is late with their project then they will not get any living expenses for the remaining number of months. Every year they have two or three such cases. 

Problems


They are not responsible for my project timeline: This is not really a problem but both of them made it clear to me on the first day. In the beginning the supervisor told me that you will be the one driving our discussion sessions and deciding your work for each week. The Phd student also told me that "I am not responsible for protecting the timing of your project and you are responsible for that". So I cannot blame them for any delay.
Unwilling to Negotiate: The problem is that my supervisor is not willing to negotiate anything related to scope or requirements. The first time I tried to bring up the issue of scope, the reply was "We will see near the end of the project what happens". The second time I tried to bring it up I got a bad tempered reply of "To be real blunt, this is what I want in the end. If you are worried about your grade then I must tell you that you will be given a fair evaluation".


What does a "fair" evaluation mean? Does it mean I will get the degree but I will work two more months after my project timeline without pay and also lose my new job?  In that case, this is not really fair at all.


Unrealistic Expectations: Now for some reason I feel like that it might not be possible to complete the three goals of the project on time. It might be possible and it might not be possible. I am not sure of the time because I have not done something like this before. And I think that the supervisor is also not sure of the exact time it will take. For example, When I asked about the first goal then the Phd student said it is really simple and will take around two weeks. However, when I started implementing we found out that there were a lot of things to implement just to support the simple thing and it is much longer than just two weeks of work. 
Trying to change directions/ Integrating my senior's work: Furthermore, I was requested to also  integrate this project with a senior's project.
Sometimes they want me to go in a different direction which is again scary for me. 
They ask me to write down the project goals so that could be used to evaluate my work in the end.


Solution?

I am really stressed out about the timely completion of my project. I am currently working really hard and don't even take the weekend off. My colleagues are only working 9 to 5 from Monday to Friday. This is the reason that I am already implementing things while they are still studying papers for their topic.  

How should I deal with this so that I complete the project on time ? How do I set realistic scope and goals for my project without crossing my supervisor? How do I make sure they don't ask me to do something in the last two months that would make me late?
You are still 7 months off. Work hard, but don't overwork yourself. 3 months before the deadline, re-evaluate where you are are: either you will catch up, or more likely, you will fall even further behind. If first, great, you win, if second, you now have a much better leverage to force descope of the project. Go to your advisor and say: ok I've been working really hard for 5 months, this is what we got, this is what we didn't and it was due to these unforeseen circumstances. Then make it absolutely clear that you plan to leave after 3 more months due to a job offered and that it is hard to buy food with no salary. She will probably huff and puff, whatever, at worst your grade won't be perfect, but then again, if you have a job lined up, it shouldn't matter. Whatever you plan to do after that job will be judged more on that job than on your (possibly) mediocre grade.