How do I know if my vision is bad if im always straining to see?

To start- I’m making an eye appt today.

I’m pretty sure my vision is terrible, but I think Ive been straining/squinting for so long, I don’t know where my “normal, at rest vision” is. Does that make sense?

I see fine right now, but I have headaches, my eyebrows are always pinched together, I’m very light sensitive, and my eyes always feel a bit uncomfortable.

I think I can see clearly, I’ve been to the eye doctor before and was only given a very weak prescription. Could I have been over compensating or straining my eyes to see during the exam without realizing?

When I close my eyes and relax them to the point that they don’t feel worked or strained, then open my eyes without refocusing, everything is insanely blurry before I adjust and refocus my eyes. Is that my true vision?