Welcome to our Forum and thanks for your questions, as well as your confidence in our services.  I'll do my best to help.  I'll focus my comments on HIV which is the problem that you appear most concerned about although much of what I am saying will pertain to other STIs as well (I presume your MyLabBox tests was one of the panels which included tests for other STIs such as gonorrhea, chlamydia, trichomonas, etc.).  First a comment on your partners.  Most people, even most persons who have used drugs in the past do not have STIs and most single unprotected encounters with infected, untreated persons do not lead to transmission (chances of getting HIV from any single encounter with an untreated, infected person is less than 1 in 1000.  Further your testing provides almost certain assurance that you were not infected by either of the encounters you describe.  As I read it, you have now tested several times since the interaction with your friend and had you been infected one of those tests would have certainly been positive.  Regarding your June encounter, you had another unprotected exposure.  While shorter exposures most likely have a lower probability of leading to infection, the precise relationship of the duration of exposure to likelihood of infection is unknown so testing was a good idea. 

More and more people are choosing to do their testing with home tests such as you did.  My own personal experience with MyLabBox is limited but I have reviewed material from them on-line and everything I can find indicates you should have confidence in the results you had.  Certainly a test taken 11 weeks after an exposure your be completely reliable.  Further, I note that on their ads then note that they have been certified for their performance by CLIA, one of the nations most widely used lab certification services.

I do not see a need for further testing or for testing using venous blood.  You should certainly be in the clear and there should be no need for further testing related to the encounters yo u have described.

I hope these comments are helpful.  EWH