Good suggestions up there! As for making a deal with your mum, here are some suggestions to get her off your back (and possibly to convince her to still pay for you)

Choose the degree you want and tell her that if you don't like it after a year, you'll switch to something else (but don't say that you will switch to Engineering or she will expect it)

While taking your basic classes (fresh and soph), take ONE introductory class in Engineering alongside introductory criminology and justice. Just one, not any more than that. Show her that you're looking at other options, including the one she suggested (but you know really you wont pursue it. Sounds like a waste of time, but at least she's still pay!)

Say you will major in Criminology and minor in Engineering, and you'll switch them round if you later prefer Engineering to Criminology (but when it comes down to it, half way through your degree you probably would have proved to her how much you like Criminology and you won't be minoring in Engineering anymore.)

Or... you could go it alone. Hard choice when you're young, in full time education and need to pay tuition. If that does anything, it may prove to her after a year of struggling with it that you're determined to pursue YOUR dream, and not let her live through you. Then she'd probably jump back on the wagon and pay or you but I'd use this as a last resort.

Whichever route you choose, either based on all our suggestions in this thread or your own, good luck with it! There should be a way round, and showing your maturity in making decisions should make sure she won't hate you for it.