Maths or engineering?

It sounds to me like you're in a similar situation to what I went through in 6th form.

I was dead set on doing maths, I always enjoyed it throughout school, was on for near perfect marks in A level maths & further maths, and so I had no hesitation in applying for a degree in it.

Anyway, I start my degree and for the first year it all goes fine, I get decent marks and quite enjoy it, but as second year progressed and the work got harder I started to struggle with it, and one major reason was because I found myself thinking "what's the point" when absolutely everything is purely theoretical, and there is no end product other than something on a piece of paper.

Anyway, I switched to engineering and found it suits me a hell of a lot better. Instead of everything just being theoretical, the maths you do is working towards a proper, real world point, so you can appreciate the real outcome of what you're doing.

There's also the added bonus that engineering is a hell of a lot less boring at degree level than maths is, although having said that I have spent the last 16 hours staring at 3d models of plug sockets!

What exam board did you do Maths a level on?