I'm 5 months post 2nd baby, 5'11, size 14.
For first 2-3 months I lived in total comfort clothes - yoga pants/jersey pants and tunic-style tops with Uggs (it would be flip flops if had had a summer baby!).
Last month or so I no longer look pregnant (although still got big tum and muffin top. Gah!). My new style is dresses over leggings, with boots (but will swap to gladiator sandals or flip flops when weather allows).
Leggings have to be black and extra long. Dresses need to either be wrap dresses or have a deep v neck (emphasise norks while I've got them!) and 'drapey' front ie. not tight/clingy around tum, but also not totally loose/baby doll-style like a maternity dress (live in fear of people thinking I'm still pregnant!). Patterns in bright colours or black are best (other 'blocks' of colour don't seem to be very slimming on me).
Check sales at White Stuff / Fat Face. Also Great Plains website is OK. Warehouse. New Look, Oasis, Primark, Dotty P's all go up to at least a 16 and have reasonably trendy styles. Topshop & H&M have some OK things among the 80s-tastic teenybopper monstrosities!
Get some cheap jewellery and scarves etc from any of the high street shops to jazz up all-forgiving black if you aren't brave enough for anything more.
Topshop or M&S for best quality leggings/thick tights.