Blood work prior to IUI?

Destinee

I went to my RE for my consultation and he advised we didn't need to do blood work.. and that we would do HSG once my period ended and then Sonogram closer to ovulation time and a trigger shot if I have eggs that drop.

So I went to my OBGYN and got blood work and everything is fine! Aside from my b12! Its at 501 which is 50 points away from being right in the middle, 901 on considered excellent but she wants me to wait to conceive once I'm 1100!

Anyone else have experience w/ this? My RE doesn't seem concerned but my OB worries about tube defects. I'm on supplements now. I feel like I'm in the middle which is considered "normal" so it should be fine.