I am so very sorry for your devestating loss.
I haven't been in your exact situation but I have lost 2 children my son was 11 weeks old and my daughter was 2 weeks old.
Firstly you need to remember that your body has still gone through a birth although your little boy isn't here your body will react the same way as if he were. You need to see your doctor about getting something for your milk supply, the last thing you need is to be worrying about that too. I can't remember what I was given but I know there are various drugs.
Secondly you need to prepare yourself with an answer, people will ask and you don't want to be caught offguard. I kept it pretty short because I knew I couldn't handle going into details with aquaintences in the early days. Also for down the line prepare yourself for people asking how many children you have, I never put any thought into it and the first time it happened I stood there with my mouth open not saying a thing because I just didn't know what to say.
There are still things you can do for Thomas just now (if you are having a service for him). I found this a comfort somewhat but I wasn't prepared for after the funeral, DH was due back at his work when I needed him most and I wish I had someone around for at least a few days afterwards.
Don't look to the future and hope it will get better in x weeks or months, just now take every minute at a time and live through that, in a little while you can start thinking about the days ahead, then eventually weeks, but remember this road lasts a lifetime so don't let others push you into feeling better or putting on a brave face. This is your reality now.
Don't be in a rush to do anything with his things. If you don't want them around then box them up and put them out of the way but don't be hasty, how you are feeling now is no reflection on how you could be feeling next week.
I'm not sure how old your daughter is but I found this story very good for explaining loss to my kids.
Please be gentle on yourself, include your daughter in this too and don't be afraid to let her see you cry, don't push your DH away either you need each other.
I am just so very very sorry, I remember the first days all too well, but I promise you do get back to some sense of your new normality eventually. I'll light a candle for little Thomas when I light my babies candles later on tonight if you don't mind xxxxx