None of what you've mentioned sounds braggy to me
I guess it depends on context. Mentioning buying something top of the range for your baby to another mum who was struggling financially wouldn't go down well.
How are you at reading other people's emotions? Can you pinpoint the moment that other people go off you? Any examples you could share?
Not agreeing with somebody else is fine and allowed; but sometimes it's not tactful or kind to point that out, and it can stop the flow of conversation, especially if it happens quite often. I wouldn't point out I disagreed with somebody if they were obviously proud or happy about something, or if I could tell it was important to them. I might use the tactic of getting curious, asking questions about it and trying Rio find one little part of it I could admire or agree with. For example, a friend might tell me they are proudly voting for ukip. I cannot stand anything about ukip but if I say that to them, it would only cause friction and discomfort. I do know they have one or two policies I like (education, iirc) So I might mention that I like their education policy. I'm not selling out by agreeing that ukip are great, but I'm not putting my friend in a position where she feels judged or looked down upon either. Truth be told for that example I'd probably more likely deflect the subject and change the conversation to a different subject entirely.
I believe I could also come across as quite braggy.. maybe and also probably quite judgemental.. sometimes. I just can't help myself.
The wording here is quite telling. You CAN help yourself, you can modify your own behaviour including what words come out of your mouth. Take personal responsibility for your own words and actions.
You can also learn to like and love yourself better.