Liz, I know that you have yo-yoed on these issues A LOT since moving in with your BF. I know that you start to have (very real) concerns about your BF, and then he does or says something to make you feel good, and then you flip the issues around on yourself and seem to let him completely off the hook.
Here are my thoughts, which are worth nothing more than the figurative paper they are written on.
1. I'm with you on "I love you." I get that plenty of people do just fine in environments where they don't here it much or at all. I have a hard time imagining myself being OK with that, but we all have our different priorities and different things that matter to us in relationships, and I totally get that for many people it's just not that important. But it's not merely an issue of not hearing it much or at all. Your BF has essentially told you that he doesn't feel that for you yet. That is a whole different ballgame, and one that would also upset me terribly, given that you guys live together, you pay half his mortgage, and he has this apparent expectation that you will contribute to an expensive car without ever discussing it with you.
2. I know that you have expressed concerns in the past about your BF's feelings about your son. I totally understand being conflicted about that, and the whole thing being complicated by the fact that you feel so much guilt over not holding your son more accountable throughout his life (been there, done that, have the t-shirt). I think it is 100% fine for your BF to express his concerns to you. I think it is 100% fine for your BF to be involved in "parenting" your son to the extent you are comfortable and to the extent that it is not overwhelming to your son. But I very firmly believe that a step-parent's (or BF/GF of a parent) primary job is to support the parent, especially during the first year or two of a blended family. I think you were right to be unsettled by the forcefulness and controlling nature of your BF's attitudes about your son and his insistence that you make drastic changes to your parenting choices to accommodate HIS opinions about YOUR son, who he has honestly not known for very long and who is very nearly an adult. I think it may be easier to transition into a full parental step-parent role with younger kids, but with teens? It's much harder. I know your son needs more structure and more accountability than he has received in the past, but I'm not convinced the right approach is to do a complete 180 and turn into a team of drill sergeants. I can almost guarantee that such an approach will leave him resenting your BF, because he will (rightly) ascribe all the changes to your BF's different parenting strategy. Remember, also, that your BF has never parented a teen boy. He has never parented a child with special needs. I get that you need to change some of your own parenting choices, but that doesn't require a wholesale abandonment of how you've done things in the past in favor of how your BF thinks this should all be handled.
3. Oh, the car. And the finances. I feel you on that. I really, really do. I tend to agree that if you offered to pay half the mortgage when you moved in, well...it's not fair, but it is what it is. That said, I ABSOLUTELY believe you have every right to raise the issue with him again, now that you have all lived together for awhile. There are always growing pains, and various understandings develop over time as you share living space. I think you are very justified in reopening the issue with him, expressing your concerns, etc. This kind of stuff was a HUGE issue in my marriage to STBXAH, who made it very clear that he believed I had an obligation to pay half of everything even though I brought home so much less money than him. It is a horrible way to live. If you feel comfortable and safe bringing it up, though, I would do so.
But the car. The CAR. No. Absolutely no. I would NOT agree to participate in that financially. I would be very upset if someone made that decision on his own even if he planned to pay for it all himself! You don't build a life with someone, and combine households (even if finances remain separate), and do something like that.
My bottom line is that you have been having these doubts for the duration of the relationship. You might push them down temporarily in the wake of a great date, or a sweet text, but they always come back up. That says something to me. You work hard on your recovery. You have grown so much. Please don't dismiss your feelings as an indication that YOU are maladjusted. You have a right to your feelings, and they are perfectly legitimate feelings.
Love you, my friend. Good luck on your Series 7!