Mother tongue (father tongue?)

My kids have neither :(
I am maharashtrian and my husband is gujarati. After marriage when I went to 'sasuraal' everybody talked to me in gujarati (even my husband). My sweet B-I-L was my translator. Ours was a "love marriage" so my first goal was to impress my in-laws. I made up my mind to learn gujarati. (mostly it was bcos I wanted to know what everybody was talking about me. It was easy for them they could talk right in front of me.) A few times (actually a lot) I sensed that my MIL said something very nasty but, I still don't know what.
Anyways, like a 'pativrata' I started learning the new language and so I was able to understan if they talked slowly. I was so proud of myself and so was everybody else.
Even after coming to US I continued to speak gujarati and now I am very fluent too. But, in all this marathi got lost somewhere. Though I still speak with my father/brothers/sister in marathi, I have started (already) losing the touch.
My son spoke gujarati till he started going to school. Now he speaks only if wants to 'butter' me. He is 9yrs old now. He understands Hindi a little bit and some of gujarati but no marathi - sob sob...
Now my daughter who is 4 yrs younger than him didn't speak any Indian language at all. Her first words were 'no'.
I speak with them in gujarati and always get the answer in english. My son used to go for Hindi classes at our local hindu temple. But, after the basic alphabets he quit.
It really makes me very sad that I didn't pay enough attention. I should have been consistent and should have made them speak our language. My dad and everybody from my side of the family keep telling me to talk to the kids in marathi. Its like starting all over again.

I wanted you ask you guys how do you deal with language issues.
If you ask my kids what is your mother tongue, they would say, "mm....pink!"