回复：着急啊…………还得继续求救！！！

I think your understanding on the grace period is wrong. You are still out of lawful status when you are in the grace period. GP is used to prepare for leaving this country, not for extension of stay. It is very doubtful if you can change your status to other nonimmgrant status during GP.

In your case, you are close to the 180 days limit. You must file H4 as soon as possible (even though it is likely that it will be denied). When your H4 is pending in USCIS, file I-485.