Are companies actively telling you that you don't have enough experience, just not responding, or are you getting discouraged by the job description? Having written many job descriptions, a lot of it is a negotiable wishlist and actual numbers of years is maybe one of the squishiest bullet points on the list and is more indicative of maturity and overall work experience vs exp in the role. Lots of PMs (not junior/associate/assistant PMs) get hired with just some "business" experience (finance, consulting, marketing, etc.). I don't think you should have a problem as long as you can demonstrate the qualities of a PM.

You may also want to recraft your resume to be more pointed about your PM experience and less focused on your engineering aspects. Here are two great threads on Quora that can help you pitch yourself to the questions hiring mgrs might want to see.

http://www.quora.com/What-are-frequently-asked-questions-in-... http://www.quora.com/Recruiting/What-are-useful-interview-qu...