I am not much smaller than you bro so I don't think size is the problem.I'm not that big, just average, Ada never has had problem with me, even though its not really a deep deep throat exp for me.
Ada can be great I think that to get the best from her you need to see her early in her shift and preferably on a Friday after she has had Wednesday and Thursday Off.
I have seen her on a Tuesday and a Sunday as well as a Friday and IMHO she is always better first up Friday.