Welcome to our Forum. Your risk for having acquired any STI from the encounter you describe is quite small. Let me review why I say this.
First, I suspect your partner did not have any STIs. Most people do not, even those with multiple partners, and the care with which she approached you and her statements about regular evaluations suggest this to be the case.
Second, even if you had not used a condom for most of the events, most exposures do not lead to infection.
Third, you used a condom for vaginal and receipt of oral sex. Condoms are highly effective.
Fourth, amongst sex acts, cunnilingus is probably the lowest risk for acquisition of any STI.
Fifth there is no risk to you from masturbation of her with your finger, nor of transfer of her genital secretions to you on your (or her hands).
Sixth, you remain asymptomatic. Most STIs would have caused symptoms by day five following exposure.
For all of these reason, I think the likelihood that you acquired an STI from this encounter is vanishingly low. I see no medical reason for testing. Whether you need testing for your peace of mind is another story but I certainly would not be concerned.
I hope this assessment is helpful. EWH
Your response was quite comforting. Still, there remains a lingering concern. However, since it has been at least 17 days since the encounter and I have had no symptoms, are there any STI's that I can rule out and then limit testing to only those STI's that do not have obvious symptoms?
All STIs can be asymptomatic. I suggest that you go on and test if your feel you must (I would not), At this time testing for gonorrhea, chalmydia and NGU would be defintive. EWH