I'm sorry your children don't come with you any more, and I think it's really admirable you've taken them on your own up until now. That will have given them a fantastic grounding that hopefully they will come back to. It's great you don't feel they've lost their faith altogether too, I remember something in GCSE RS about private/public worship. And some idea that teenagers often reject church for a while, but explore their own relationship with God privately?
In terms of them coming, is there a Sunday evening Mass somewhere if they'd like to see friends of Saturday pm. Could you make it into a treat, go for pizza afterwards, that sort of thing? Could you discuss with them and say something like "I'd really like you to come to Mass, what's putting you off?" And see if you can work round their objections (time of day, length of service, would prefer different church etc).
Out of interest, how did your DC stop coming? Did they just say no one day? It would never have occurred to me to tell my mum I wasn't coming to church! I suspect she was just really strict and I was a bit scared of her... I have younger DC and wondering how I might deal with this without being a tyrant! I think your absolutely right not to "force" them but I wonder how people do encourage reluctant teenagers to go to church?
If it's just not an option that they come at the moment you might be interested in this:
www.mothersprayers.org
It's an organisation for mothers getting together to pray for their children and grandchildren. There might be a group in your parish (or you could start one?)
Apart from praying for your children, it would hopefully give you some support too, especially if you're now going to Mass on your own.
They actually have this quote on their homepage
'Stop your crying and wipe away your tears.
All that you have done for your children will not go unrewarded.
They will return from the enemy's land.
There is hope for your future.
Your children will come back home.
I, the Lord, have spoken'.
(Jer 31: 16,17) Good News Bible
Sorry that was long, (and sorry "enemy's land"sounds a bit strong!). I do think you've given them a wonderful base to come back to and sounds like this is very typical of teenagers who do later come back to going to church.