Personally, I think the best thing in a blow job is the excitement of the women, so when they do it without liking it, it sort of turns me off. When they get excited or even come after they lick and eat your sperm, it is a completely different job which literally blows my mind. A blow job should always blow your mind. If your girl is afraid her genitals could get in touch with your sperm, suggest her to swallow it in the first place. She cannot really believe one can get pregnant by eating sperm: if that were possible, the inner foundation of the christian religion would be based upon on a blow job!
About the circle device, I have a 12 oz. one, it is comfortable and I think it works on the long term. So far I am using it as an ADS but I also hang, pump, clamp, jelq, kegel and everything. I cannot say what exactly makes my dick grow. I suppose PEing works the more you apply to it and an ADS is a good tool. It is definitely possible to make an ADS similar to the circle device without spending a lot of money as you may build a pump a hanger or any other thing.