Risk can not be ruled out. Testing recommended.
During intercourse, your organ had been exposed to the vaginal secretion for few minutes. HIV
can spread through intact mucous membrane
also. Cuts and abrasions may facilitate this transmission. Sometimes, our organ might have microscopic abrasions which we can not notice under normal circumstances. Bacteria are smaller and seen only with the help of a microscope whereas Virus are still smaller not able to identify under ordinary microscope which can magnify about 100 times. Virus needs electron microscope to visualize the same. Now you can imagine a virus, how smaller it is. It can enter into the skin and mucous membrane even through a microscopic pores.
So the risk can not be ruled out. At the same time it is not having any higher risk. Many a time sex partners of these HIV positives remain HIV free for years together even after their prolonged exposures without any protection.
They are called as Sero-discordant couple.
It once again depends upon various factors. Nothing can be predicted and so we have to be cautious and rule out the possibilities totally by test. Protected sex is always safe. Unnecessary mental tension can be avoided.