F2 -> H1B -> F2 again? (F2 visa not stamped "cancelled without prejudice")
 

Hi,
I first came to the US with a J-1 visa in 2001. A year later, I applied
for another J-1 visa and the first one was stamped "cancelled without
prejudice". I got married in 2003 to a foreign student and my status changed
to F2 - the previous J-1 visa was also stamped "cancelled without
prejudice".
About 6-7 months later I found a teaching job and my school sponsored me
for a H1B visa - but this time, the F2 visa was NOT stamped "cancelled
without prejudice". Never had any problems when driving back to the US from
Mexico (we live in Texas and visit family there fairly often).
Now that my husband graduated, applied for OPT and got a job, and we had
our first child, I want to go back to F2, but I am wondering if I need to do
anything at all, since my F2 visa was never cancelled (it will expire in May
2007). I am on maternity leave right now, but won't be going back to work
next school year (my resignation will be effective as of June 1, and I will
be considered a school employee until the beginning of August). Do I need to
get my H1B visa cancelled? If so, how would I do it?
Anyone with similar experiences out there, or at least some advice as to
what I should do to make sure I'm never out of status?
Thanks for your help!

Maria