The size of the plasmids that can be propagated in DH5 alpha depends on the specific plasmid being used. This picture shows that the DNA concentration is very high. Dilute 10-500 ng/µl before the gel check and use the ladder that maybe easy to understand.

DH5alpha does not carry any plasmid, but of course it is a host for recombinant plasmids. So only you would know what size the plasmid was depending upon what plasmid you put in it (or was in the strain that was given to you). But DH5alpha alone does not carry a plasmid.

But from the figure you show, the very bright fluorescence in the middle of the gel is probably RNA and the faint bands at the top might be plasmid but most likely are just some genomic DNA.

Why do you ask about the size of what you have isolated and don’t put DNA length markers? Do a new electrophoresis with DNA markers, then in the end you will see what you have isolated: genomic DNA or some kind of plasmid!!! However, one more thing: it looks like you have a lot of RNA in your samples!!!! To make sure that the samples are contaminated with RNA, treat them additionally with RNase and then apply them to the gel.