Dear Bhargab Math,
Why are you so tensed. Just relax. Your time will come soon. You will come to know what happened then how.
As for your reply, when I sucked my girlfriend boobs she like.it very much. She wants me to carry on. Oftenly she just close her eyes or put her hand in my hairs and massage them and asked me to do more kissing and sucking.
So just relaxed, if you have no gf then don't be upset just concentrate on your studies, get better secured life and married to a beautiful girl and fulfill your all dreams. Good Luck .!