NO STDs show symptoms just two days after and exposure. Kissing and sucking nipples would have never exposed you to any STD. The can expose you to mononucleosis, flu, etc.
Your sexual encounter was protected. Some STDs can be spread even when condoms are used. I am talking about syphilis, herpes and HPV. You can test for these ones as follows:
-6 weeks after the exposure, for syphilis, and if your result is negative, repeat it 3 months after the encounter, as there are people that take longer to show a positive result.
-3 months after the encounter, for herpes.