The Lact-Aid should help with this problem (although I'd strongly urge you to buy more than one unit!).
You mentioned it's hurting your supply - are you pumping after feeds?
Good luck boosting your supply, mama. I always had to supplement DS1 but after a bit of a rough start - including supplementing with the Lact-Aid, domperidone and pumping - I've been able to EBF DS2.
Do you think your baby's latch issues are causing your supply issues? That was the case with my DS. What worked for us was a) ditching the SNS completely. Personally, it just did not work for us because I did not get enough stimulation when we used it as he was lazy with it and b) nursing, then when DS had tuckered out on nursing (usually 10 minutes each breast...he was preterm so latch and exhaustion issues were magnified a bit) I would give him a small bottle of pumped milk, then would wait an hour after the nursing session, and pump for 10 or 15 minutes each side. Then I'd save that milk for after the next nursing session. We would nurse, bottle, pump about 8 times in 24 hours. The first month was a little rough. Then he magically "got it" and we totally ditched the pump and I never used that thing again (hated it after having to use it so much). But, it worked. By three months adjusted age, he weighed 16 pounds (born at 6lbs) and was EBF. We didn't use bottles after that month and actually when I tried to start using them around 3-4 months so I could go out to dinner or whatever, he wouldn't take them, so the bottles definitely didn't screw up his nursing at all. Good luck mama. You can do it.
Megan - I did get my LactAids in the mail and I like them better than the SNS, for sure. I'm still having issues with her latch - it's ok, but just not the same strong, vacuum type latch she had before we introduced the devices. I'm working on having her nurse 'bare' more often, and though she's resistant, it's getting better. I'm also pumping more, so I'm thinking that is helping build supply, though not as fast or drastically as I'd like!
APToddlerMama - I do think the current latch issues are related to a slight supply drop, but I have a history of low supply, so that's not the whole issue, just a part. I'm unsure exactly what causes my supply problems, thinking it's something hormonal at this point, though there are other issues related to the SNS/latch that are compounding our problems. I'm still working at it and hope to keep building a supply, even if it can't be a full one.
Thanks for everyone's feedback/suggestions.