I would keep the crossed over secondary away from the primary turns, like give it at least 1/2" space. I would also use enameled wire or an insulation with good RF properties like Teflon. Some general purpose wire insulation is very bad in an RF environment. I also see some glue on the wire, be careful with that as anything on the wire can change the dielectric constant. I found black RTV on the wires will completely screw up the transformer.
Here is a picture of a commercial MyAntennas version, the gold standard. Notice the twisted pair primary turns fairly close together as is the first five turns of the secondary, then after it crosses over and gets higher impedance there is more spacing between turns so the output is far away from the primary.
This was a factory MyAntennas unit that I took apart and put in a smaller box, but the raw transformer is stock as shipped.