Just a thought,..but when you are planning 'communal living' at a stage of NRE and 6 months in, this COULD be why Anne doesn`t take you very seriously.
Maybe she has been witness to Bob`s grandios ideas`s before,..Or, maybe she isn`t taking you two seriously until you are both past the NRE ? Who knows ? You say she hasn`t been 'successful' in looking for a long-term relationship. Are you sure about your outlook on that ? She could be a person that is perfectly happy not rushing into things. If that were the case, she is most likely only judging you by her own standards.
If she is happy for Bob, and doesn`t interfere in plans, dates, or try to get him to end things with you, I doubt you are dealing with jealousy over your 'youth' or whatever else.
Also, it sounds like Anne might be trying to 'educate' you on things you have no experience in. It feels undermining to you. Rather then start a tug-o-war about this, why not actually take her advice on things she has experience with ? Ask questions. Learn.
The things you have experience with in life, you can take the lead on those topics. Set an example, and maybe she'll ask questions in turn, and your confidence will receive a boost.