I know that feeling. I spent a number of years not being able to weigh in at my doctor's office since the scale only went to 350. I list my starting weight as 353, but I was likely a good bit heavier than that but I had no way to weigh in since I also didn't have a scale that would weigh me.
In the end, how you feel is most important, but you will want to know where you started. Also, while denial might feel good, it isn't a very healthy place to be. Also, sometimes not knowing is way more stressful. Once you have a number it is just that - a number.