Only moderate confidence, but not a complete guess.

She is saying that at that time she was not paying him any attention: "Por mi pasabas desapersibido".

I thought at first that "y otra que andava en mis volas" might mean "and another girl who was pissing me off". One common meaning of "bolas" is "balls" (testicles), of course, and so "andar en las bolas de alguien" would mean the same as "darle en las bolas" or "romperle las bolas" (like "tocarle los huevos" in Peninsular Spanish. The following text, part of a comment on a YouTube video in response to a previous negative comment, might tend to support that (here with the sense of insulting someone, apparently):

"no mames nadamas porq el tiene los huevos de subir y hacer un grandioso espectaculo no signofica que tienes que andar en sus bolas diciendole que la esta cagando.... CABRON yo te daria 1 peso nadamas porque tu te subieras a cantar enfrente de 5 personas......"
http://www.youtube.com/all_comments?v=-riIh-rR6Pg

However, I think the meaning I have suggested is much more likely. It fits the context, and seems to be what the expression means in the following examples too:

"christian chanchito lindo te kiero ver corazoncito darte mushos vesitos xd te veo hoy espero ojala (yn) ya k ayer estavas en tus volas y no te vi en todo el dia mil cosas k hablar chanchito lindo te amoo bebe mio eres [...]"
And more in the same vein.
http://www.fotolog.com/valentinaa__paz/26930477

"puse esta [foto] q refleja mi lado pensativo
y una xikilla por hay me llamo xiko existensial por
esa forma de poner me asi,entonses asi la llame
en realidad ese dia andava en mis volas y pensamientos turvios
y cuaticos (siempre tenemos uno ovarios dias asi)"
http://www.fotolog.com/flaxer/27021818

"No estaba muerto...
andaba en mis volas"
http://www.fotolog.com/zancu2/12843970

"mas encima andaba en mis volas de depre"
http://www.fotolog.com/o0_kotita_0o/13509795

"oe te vi te salude i no me peskaste o_ó"
[...]
"perdon andaba en mis bolas :B"
http://www.fotolog.com/only_visual_fan/21246299

So it's rather like the European Spanish expression "ir a su bola".

I think "y otra" simply means "and another thing" or "and also".

"Tu cachay" (which should be spelt "cachái") means "you understand", with the Chilean "-ai" ending:
http://forodeespanol.com/Archive/ElFamosoCachay/lbp/post.htm