I have a 2 year old female chihuahua who I have bred on her last two heats.
Both results in ties that lasted between 45mins-60mins.
My stud dog is proven, hes gotten 2 other females pregnant in last year, so hes not the problem.

My female wasnt progesterone tested, we bred for 3 days, she was flagging and standing etc.

We really want a litter from this girl.

Any ideas on improving the odds on her taking on her next heat which will be round April?

Wheat germ tablets may help if all other factors are correct.

Snap except my champion bitch has successfully had two litters, I am going to try one more time.

If you don't get her pregnant on her next season it would be kindest to have her spayed.  The breed needs to whelp well before they are 3 years old for a first whelping.

When you say that you "bred" her on 2 seasons I am assuming that you didn't actually breed her, merely mated her.  Correct me if I'm reading this wrong.

Have you thought about using an outside stud.  From a decent breeder obviously.

Has it been the same male on each of the matings? Maybe they just aren't compatible, I'd look for a different stud for next time who is proven and not old

Also I'd progesterone test too even though a mating has taken place it may still not be the right time.

She may just not be fertile, for some reason.   We had a visiting bitch who came to one of our (proven) males and missed.   She came back, to our other also proven, male on her next season, and again missed.   Both times she had a couple of good breedings.   She then went to another stud dog on her next season and again missed.   After that they gave up!!!!!