Uy, sciatica sa first trimester pa lang, that's rough talaga, lalo na first baby mo pa! I'd really recommend checking with your OB about this kasi it needs proper assessment, but honestly a few of us mums had similar nerve pain and most of us found it got better with stretching, prenatal massage, at proper posture (sitting straight really helps, kahit uncomfortable hehe). Some swear by prenatal pillows para sa side-sleeping position, and warm compress din helps temporarily, ang isa sa mga kaibigan ko nag-PT din throughout pregnancy which made a big difference. Fingers crossed your doctor finds something that works para sa iyo!