Adventures in Potty Training!!

First off, let me start off with I HATE potty training!!! So we started last week.. I was so sick of changing 2 kids diapers and Sienna always taking hers off and bringing it to me so the adventure began! I put her on the toilet every 30 minutes the first two days and by the 3rd day she just would go and sit on the toilet and go. GREAT I thought!! Well I just let her walk around naked and so now when I put her in clothes she goes in her pants! Well she is getting a little better with that one if we are at home, but it's still a pain. So today we are at the grocery store and she tells me she has to go potty, so off we go through the store and into the stall. Now this is not an easy task with 2 kids. You have to load Austin in and Sienna AND your diaper bag AND attempt to hold her up on the toilet while your trying not to gag. She has a little toilet seat that goes on top of the toilet at home. Well she won't go in a public bathroom without that dumb thing. She wants her Elmo seat to put on top because she says shes going to fall in!! So after 3 times of her saying "potty mom", trekking us all in there, and her screaming she finally pooped and peed in her underwear! AAHH!! Help! She does GREAT if we are at home or somehwere and she has her Elmo seat. I know it's only been a week but do I seriously have to pack her Elmo toilet with me? As if I don't have enough crap to pack around with a newborn and 2 year old!! If there is anyone out there reading this, friends, people who you know, ANYONE-- I need advice! How do I get her to 1) realize when her clothes are on you still have to go on the toilet and 2) go on the normal sized toilet?? I seriously am going to go a little insane here! Thank you, thank you, thank you!

I should be glad she goes at home all the time now with barely any accidents but we need more than that here!