Another nursing pg mama chiming in here!
I've been either pg or nursing (or both!) for over 7 years now, yikes! :LOL
This will be my fourth pg while nursing, so perhaps some of my past experiences would be helpful?
For me, the nipple soreness isn't a constant problem, but rather goes in phases -- first few weeks (i.e. right now!) I'm sore, then okay until around 18-20 wks., that lasts for several more weeks, then another break until around 33 wks., through to the end...
Right now, in the first trimester, I'm a little sore, but more exhausted than anything! I've night-weaned all my kiddos during the first 10-12 weeks in order to cope with the extreme fatigue of early pg, all with great success (and the invaluable support of a great DH, who gets up with them at night until the transition is complete!) Knowing that I'll get some sleep at night also really helps me have patience for the more frequent day nursing.
In the past couple of weeks, Charlie -- who is almost 15 mos. -- has stepped up her nursing from maybe 5x a day to well over 10! All my other children did the same thing, so I wasn't surprised, but I admit that after the 6th or so time in a few hours, I cringe when I see her aiming for me, :LOL! In fact, she's nursing right now, b/c I'm a captive audience when at the computer!
She also nurses longer than usual, ostensibly trying to build my supply back up...
I don't usually lose my milk until sometime in the third trimester, fwiw. Loss or lowering of milk supply affects different children differently. Some definitely notice (as well the change in taste) and wean during pg, regardless of how committed you are to nursing them. Others could absolutely care less! :LOL I've found it's much more about personality than age or any other factor...there's no real way to predict!
I also think the clinginess that many of our toddlers are going through right now has less to do with our being pregnant and more to do with where they are developmentally. Many are cutting teeth and not feeling fabulous about it, many are relatively new walkers and toddlers and waver on their independence/dependence factor by the second, it seems. They nurse for comfort a lot at this age, and that can be both irritating and painful at certain points in the pregnancy.
Luckily, once they hit around 18 mos. or so, I've had very good luck explaining that mommy's num-nums are feeling ouchy, so we're going to sing (insert child's favorite song here) once through and then we'll be done with nursing for a while. I can't tell you how many afternoons I gritted my teeth through "Itsy Bitsy Spider" or "ABCD", praying for the song to end so my aching nipples could get a brief respite! But had I not set any limits to my toddler's nursing, I couldn't have made it through; it saved my sanity, I swear!
Okay, got to run to take DD to gymnastics, be back later with more if I can think of anything...