Okay, here we go:
1) No, it is NOT safe to have unprotected sex at ANY time of your cycle. Doing so puts you at high risk of both pregnancy and STD and STI transmission.
2) For condoms to be effective birth control and STI protection, they must be used for ALL contact from start to finish. Partial use is NOT effective.
FYI, unprotected oral sex ALSO puts you at risk of STD and STI transmission or contraction. Sounds to me like you and your guy need to have a Big Talk about fixing your habits before you find this stuff out the hard way, love.
If he or you can't handle that, it might be worth thinking about if you can handle being sexually active right now. So, have a think, then have that talk. Set some limits and make some firm rules, and don't bend them. Gambling with pregnancy or STIs is a losing game.
Editor and Founder, Scarleteen
My epitaph should read: "She worked herself into this ground."
-- Kay Bailey Hutchinson