-Because you do not have recent paycheck stubs, USCIS will consider you have been out of status (your status has gap) and thus, they may approve your h4 without I-94. If so, you need to go outside of U.S. to get an H4 visa to come back.
還有如果我回國需要待一段時間再申請H4,還是馬上就可以預約呢?
-Either one is OK. It is up to you. You should have no any problem to get an H4 visa in China.
他們真的不問我離境時的狀態嗎?
-Usually not. Even if they ask you, it will not affect your application.
那我現在處境是H1還是H4pending?
-H4 pending. When you stop working, your H1 status is invalid.
If I were you, I would just visit China and get an H4 to come back.