Very sad

I am 40 years and tcc for to years but miscarried twice, the last one was today I was 5 weeks +3 it was positive on the first day of my late period on January 9, I did also blood test 2 before yesterday to confirm it came out positive with a low level of HGC 347 UI/1, any tips for next time if i get pregnant how to take care of myself. If anyone have advice from experience about multivitamins that could help I never took supplements , I don't know I am confused and very sad I was having so much hope it will hold 😔 😔😔