ArcticCactus as you have identified a number of things have contributed to this it's not just your dh, although I am guessing he is a big part of it... maybe... in your shoes this would be how I would feel...
Your dh and you probably need to discuss it a bit and he needs to come up with a fabulous treat for you to make up for it (I'm thinking spa day etc/jewellery) and he needs to not forget again! Ever!
Your dh should maybe explain to his family that although the gift for him was lovely, thank you, it was not really for you and you felt left out. You may not wish to make a fuss, which is your choice, but if this is not challenged they may well do this for ever more and continue to make you feel rather sad.
My auntie never bought for dh (until this year, we've been married 14 years!) but she sends money and we (my sis and I) buy for her and me, my Mum, and for the kids - the two hubbies never minded so we never said anything. She always sent money so if we had wanted to include dh and BIL we could have but ds and B-I-L were fine and said spend it on yourself and the kids!
My mum in-law started buying me a scent that gave me a headache, I wasn't going to mention it until dh said if I did not say anything, but thank you, MIL would probably do it every year, so I told her. I love her, she is like a second mum, and she was not offended. Sometimes honestly is the best policy.
Some times not.
In my view it is not one thing is right or wrong it is just if something is upsetting or unhelpful it is best to know, if not, then not!
As far as your siblings I guess you can either accept it and spend the money you spent on them next year on yourself, or again, tell them. I am a great believer n honesty is the best policy if it will be helpful but I may be wrong!
Lastly, new friends, please do make some wherever you are, it's not easy I know. I've been an international student and an ex-pat too. But really when one is an expat one needs to go the extra mile to get into situations to meet new people. I lived where the ex pat community constantly changed so I did sports like tennis and badminton, sometimes on a Saturday morning, and language classes, and managed to meet new people through the English language school, local church and international society etc. I was not a new mum, with a baby in tow, but even so, there might be ways to meet other mums with babies or do some activities when dh can have baby.
It just looks like you are ploughing time and energy into everyone but you, and that is not a good long term strategy for you.
Good luck OP, if we were friends on Facebook I'd be sending you message... bless you.