transferring to SLO is pretty unlikely unless you relocate to a CC they consider ‘local’. As an institution, they simply don’t make much room for Jr transfers - something like 12% of the # of freshman admits, overall - and even less for Engineering. Also, by charter, they must give preference to CCC students from schools designated as ‘local’ - meaning most of those 383 Engineering admits came from Cuesta or another ‘local’ CC.
https://admissions.calpoly.edu/prospective/profile.html
Normally, i’d suggest you stay put but, since you want to switch to a major you can’t really replicate without an accredited program - i’d find a way to take a Civil Engineering class or two (perhaps a local CC) and, if it still turns turns you on, look elsewhere. I am not suggesting you not apply to SLO - it can happen - just include more accessible targets like the other Cal Poly, as well as Sac State, Chico and San Jose.
Good luck