i part-time and late-start EC'd both my older two. well, my second child (my boy) i kept in a coverless diaper and changed right away until he was about 4 months old, then started occasionally offering the potty like upon waking, then around 6 months did it more consistently but still always used diapers and had many, many wet diapers to wash at the end of each week. my oldest i didn't start with until 9 months old, and until she was about 12 months only did wake-up pee and potty whenever i had to go or if she was really telling me (which she sometimes did, crawled over to potty and grabbed it, etc. but not consistently by any means). DD1 was completely miss-free at 27 months (one month after DS was born). DS was a little different, he could tell me pretty consistently from an earlier age (like 21 or 22 months) and i could catch most of the rest, but still had a good number of misses whenever i tried to let him take over until he was about 30 months (like some weeks as much as 5-10, though other weeks were only 2-5. though we did have miss-free weeks when i offered a lot, he was not IMO a 'graduate' until 30 months). both were 100% consistent with poo around 15 months.
i think p/t EC is really awesome. i don't think there's any way my DS would've been independent at 30 months otherwise, he's the kind of kid who gets really absorbed in stuff, would wander off following a butterfly, and definitely relied more heavily on me/timing to catch but i think it worked out great in the end. i had no preconceived notions of what i was going to do with baby#3, sort of assumed i'd do it like the other two. but she was sooooo obvious and signalled almost 100% from the beginning, it seemed idiotic to ignore her so we just went with it. but she really EC'd herself - i just had to help her get to the potty until she was physically able to do it herself. and i mean she was like 15 months old when she 'graduated.' i finally sold her trainers when she was 19 months old... i'd been holding onto them waiting for the strike to hit LOL i doubt i would've full-time EC'd otherwise.
my best EC advice for anyone and everyone is to just do what you can. don't stress, don't worry, don't feel bad. try to let it become a natural part of your life, try to work it into the thread of daily living where it makes sense. i'm 100% convinced that *any* awareness that is kept/gained when it comes to elimination is a positive thing. even though i was very laid back with EC'ing my oldest two, we never had to "potty train" - eventually they just got it, i offered less as they initiated more, it was a really peaceful and pleasant transition with no stress. though i've never accomplished CLW (gentle MLW at 3 and 3.5), accounts i've read remind me of the EC process in that gradual, natural way in which it all occurs. i definitely had those moments "when was the last time i offered the potty? it's been 2 weeks!!"
I EC to enhance my connection with my kids and to make our lives easier. not harder. the last thing i need is one more stress in my life. EC made me a better, more attentive parent, and in the process helped keep my kids clean and aware.

if it's not doing that for you, then try to assess why, and try to see if it can be. if you don't feel it can be for whatever reason, then think about taking a break or stopping entirely
one suggestion i have, though, to make it a little easier, is to just offer the baby the potty whenever your older one has to go or you're offering it to her. that, combined with potty upon waking is *plenty* and hopefully wouldn't feel like too much extra work since you're there doing the potty anyway

also, when i knew i wasn't going to be trying to catch for a while (in a store, in the car, cooking dinner, stressed and overwhelmed... whatever...) i told my baby "mommy can't potty you for the next XX time, so if you need to go, it's OK to do it in your diaper and i'll change you as soon as I can." this way i felt i was still respecting her and communicating with her. and if she signalled i reminded her, "it's OK to pee in your diaper and i'll change you in just one minute honey." and then make the 'pssssss' sound to help her relax enough to go. during those times i also sometimes used a pocket dipe so she wouldn't feel uncomfortable if i knew it'd be a little while till we could get to a place where i could change her (like the parking lot, in the grocery store example).
HTH!