I am in a somewhat similar situation to you, so I empathize greatly. My daughter is a little like this too and my situation is very similar to yours, I breastfeed her still at almost eight months old and I am always with her but she still prefers her dad to me even though I do 99% of the parenting. I love her so very much, but I feel like she doesn't bond with me as much as I wish she would, and it really does hurt, so I know exactly how you feel. It is possible that maybe they are like this because they have not yet realized that we are a separate person, and they take us for granted because we are there all of the time. It's very unfair in a way because we never have a chance to miss them and they never have a chance to miss us, and I think when you miss someone it's really a good opportunity to realize how much you love and value them, but this never happens with us as we're with them 24/7. We do so much yet we receive so little.
I am very sure that he does love you very much, but perhaps he is too young to show it yet, and maybe once he can verbalise his feelings, maybe then you will realize how much he loves you. I am really hoping that this is the same with my daughter because I feel very similar to how you feel a lot of the time, and it is very hurtful, and it makes you feel like everything you do is not good enough because they don't show you the love that you so crave, but they show affection and interest in other people and it makes you feel not good enough, but it is not the case at all. As long as you are doing your best and you provide your son with all of the love and joy that you can despite being burnt out and exhausted, then you are the best mum you could possibly be for him and there is no reason for him to not absolutely love you.
Something to perhaps try is when he is looking at you, try and do funny faces and funny voices. When he looks at you, gasp, then act all surprised and happy. Also, try playing peekaboo, and every time your eyes meet his, act really surprised and excited. Sometimes, when my daughter makes eye contact with me, I will do a funny face, and I'll act like I am excited to see her, and that will make her smile and laugh sometimes.
Hey I had this with my oldest daughter and did feel like it did effect our bond as she wasn’t giving me that affection like her dad, with this baby I was so worried about that that I got referred to perinatal team who have specialists that can work with mum on things like the bond and attachment which has helped me
I think maybe look at it from a different perspective - by being with them almost 24/7 you have become such a dependable and trustworthy attachment figure that they don’t even question if you’re there they just trust you will be. You’ve given them the confidence to explore the world around them because they know you’ll always be there if they need you. Maybe it’s because they trust so much in your bond that they don’t need to seek constant reassurance anymore?
My first baby was like this. We spent 24/7 together and she was bored of me. Everyone else was a novelty but I was just the same face she saw 24/7. It’s great when they will settle for other people, it shows they feel secure and have nothing to fear. My daughter is 4 next week, we have an amazing bond and she is really independant. It really isn’t a bad thing, all babies are different