I can’t give advice on this part because I don’t know what it going to happen over the next 5 years, that is what makes this difficult.
You can only control what you can control though.
I want to say, you’re a single homeowner and that’s great! You have a job and it’s not minimum wage. I’m going to assume you’ve worked hard to get here, so give yourself a little break. If you’ve managed all that, you can manage this next challenge too.
Firstly, make sure, while you’re on 2.7%, that your 50k is invested well and returning at least 5% in an account.
Now, think about how much you have in savings. If you’ve got a nice little emergency fund, I’d start taking at least some of those 350 a month and diverting that to the mortgage.
Next, time to reduce expenses. You might already run a tight budget, but everyone has something they can cut, so think hard. Last time I went through my budget, I managed to save 240 a month. Not everyone will have this much they can cat back, but even 20 dollars is 20 dollars. Immediately put this extra into the mortgage too.
Then, think about some ways to make a little extra. Can you rent out a room for a while? Do some pet sitting or baby sitting in your home (so you can still have your own DC there). We don’t know your skill set, but there’s probably something you can do. Start planning for a more budget friendly Christmas etc.
You can do this! I’m sure you can, so time to sit down and make a plan. Between savings and a wage increase, a few cut backs, and if needed, when the rate changes, reduce the mortgage by 50k. You’ve got this!
Edited to add: Mortgage stress is awful. Ours is done now, but I’ve been there. It was many years ago and rates were so much higher, we were mortgaged to the hilt and my DH lost his job. I was working, but it wasn’t enough. I remember crying a lot too. He delivered pizzas for 2 months until he got another job, we held on by our fingernails. Stressful, but worth it. I’m sure you will be determined enough to find a way.