Is there a way I can change my yahoo mail account to a google mail account and direct all my mail to my new one?

Yes, follow the instructions at google mail.

I can’t forward from yahoo because I would have to upgrade to plus

Try using the vacation response feature, with a message that you’re not really on vacation, but are using google, instead, to resend their message. I don’t know if it would send the message to spam messages, though, that might be a potential problem.

Other than that, the only way would be to upgrade. One of the many reasons Yahoo!Mail sucks.