Cap Gap Rule :

Your OPT will expire on May 11. After that u don't have any work authorization and u don't have any status. Though u already applied for h1b. But it will only be effective from Oct 1st. In this situation, people like u will have only two options

1. Either maintain ur status by rejoining the school until sept 30

2. or leave the country and come back after oct 1st.

Majority of the students were facing this problem each and every year. Therefore, to avoid these problem, they came up with new Cap-Gap rule this year. According to this rule students like u can work and stay in US till sept 30 with f1(opt) status.

Now after May 11, ur SEVIS will be terminated....that's why u need to tell ur DSO abt your situation..so that he will update ur SEVIS till sept 30. And as a proof , he will give u a new i-20 with opt extension upto sept 30 in the 3rd page of ur i-20.....Then u will have something in ur hand to be safe.

For now totally forget abt OPT extension 17 month rule b'coz u already got selected in h1b lottery.