Starting tomorrow, I will have to work nine days straight because here in China we are obliged to pay back the cost of some of our "vacation" days. This regulation is so weird that I’m not sure whether I’ll be able to explain it adequately, but I'll give it a try. Let's consider the Labor Day vacation as an example. That is actually only a one day vacation but the government presumes we would be pleased to have a full five day vacation instead. However, their generosity comes with strings attached. We must reimburse them for the extra days! They cannot spare us a five-day vacation without cost. Ergo, we must work on weekends to pay for our four bonus days. In the service of such pristine logic, we must work next week on Sunday. Adding to the fun, our school has offered us the chance to attend a mandatory parent-teacher meeting on Saturday. How lucky I am to have landed a job with such perks! I pay for a vacation day with three days of compulsory labor. Having lost my only day off, I have to work every single day until the Tuesday after next. I think it is better to say "starting tomorrow I WILL have to ...". Normally, the word "tomorrow" would be enough to establish a future time frame, but here it is not because you are talking about a future that lies beyond tomorrow. In order to get there, you need "will". Scare quotes around "vacation" introduce an element of sarcasm. "Scare quotes" means quotes that merely serve the purpose of dramatizing a word. Since you are about to start explaining, it is better to say "I'm not sure whether I WILL be able". "Will" is helpful because none of your other words establish a future frame. "Ergo" is a Greek word, but you can use it as a classy way of saying "therefor". I introduced a bit of sarcasm.

Starting tomorrow, I have to work nine days straight because here in China we have to make up for the work we haven’t done during our vacation days. This policy is so weird that I’m not sure if I’ll be able to explain it clearly. Take Labor’s Day vacation for an example, we actually only have one day of vacation but the government supposes that it would be nice if people could enjoy a five-day vacation instead. Obviously, there’s no way that we can take a five-day vacation without consequences on the economy. We have to work on weekends to make up for the extra four-day vacation and that is why we’re going to have to work on next Sunday. What’s more, our school decided to hold a parent-teacher meeting on Saturday. So, I lost my only day off and I have to work until next week’s Tuesday. What a nuisance!