I'm sure the quitting smoking then has nothing to do with what is happening now. The only thing I can think is that 2 years older, there could be egg quality issues, but if you are getting pregnant, that might not be it. Then again, if you needed Clomid the first time to get pregnant, maybe there have always been egg quality/egg maturity issues . . . ? Are you also on metformin when you are doing the Clomid? If you have trouble O'ing on your own, or sustaining a pregnancy, there could be a PCOS issue/egg quality issue (I know that one too well) and there is a 65% chance of m/c in that case without metformin. When adding metformin back into the cocktail, the m/c rate drops down to the same as everyone else.

It just could be bad luck, too - 2 m/c is terrible, but apparently only 25% of fertilized eggs survive, so the odds just seem to really suck in general, and you might just have drawn the short end of the stick a few times. I know that explanation is horrible. Here is what I know about herbal remedies for women:
Vitex
Maca root (can be taken - NOT with Vitex) to regulate cycle, improve ovulation) BUT I've heard just as many people claim success with these 2 as claim that they messed up their cys, so I'm really not sure. I think if it addresses your problem, it works wonders, but because they mess with LH/FSH, it can also throw off cys in other people.
Royal jelly - no clue what this does, but Krissy over on the Cycle Buddies board has been using this, so perhaps ask her about it?
Some people will take Soy Isoflavones, around 150 mg CD 3-7 - supposed to work like Clomid to improve ovulation. Can be taken in conjunction with natural progesterone cream/baby aspirin below.
Some people swear that natural progesterone cream helps sustain pregnancies, and others swear by baby aspirin, and some take both. Both are completely safe during pregnancy - even if they don't help, they won't hurt. That is all I've got!
Fertility Blend/Fertility Aid - just vitamins/chinese herbs that are supposed to help promote fertility.

There are a few more listed in the herbal alternatives board that I can't remember off the top of my head, but those are about getting pregnant, not sustaining a pregnancy. I think the key for you is probably improving ovulation, and then supporting (maybe with progesterone).

Maybe post in the herbal/alternatives board? Tai/Michelle doesn't check in all the time (she is the moderator there and it is a pretty slow board), but she has good information. She normally posts over in Due in February, I believe, so you can always go hunt her down there and see if she has any additional information. I'm sorry I can't be more help.

Herbal Remedies for Male Factor Infertility (not sure if this is your issue?):

Vitamin C improves morphology
Selenium (up to 200 mcg)
Zinc
Vitamin A
Vitamin E 400 IU
L-Carnitine
Vitamin B6
Vitamin B12
Maca Root
CoQ10

Check out FertilAid for Men, and Conception XR for more information about different herbs/vitamins that help improve male fertility. Don't know that this will have any impact on sustaining a pregnancy, though - unless the failing embryos are from poor sperm quality, but it always seems we women and our eggs are blamed for failing embryos!

__________________