I play with my mother quite a lot, and I will say that I am much better than her. She just likes to play and is a great sport, so I have never had your problem. However, here is what I would recommend:
1. Let her pick the kingdom. She can pick cards that she wants to play with and that will not give you a great engine option.
2. Try new things. Do you want to see if Woodcutter is better than Workshop for Gardens? Go for it! Not sure if Mine works with Moneylender? Why don't you try? Even if your strategies are suboptimal, you will still (hopefully) enjoy yourself.
3. Play with Council Room and any other cards that give advantages to your opponent.
4. DO NOT lay it on thick. Single Province per turn is fine. Play BM/Smithy with a Chapel or something. Do not make a Council Room engine and have a Milita at the end.
5. Don't count points. It's really up to you, but not counting points makes the game more relaxed for both of you.
6. If you have bad luck (terminal collision, no village and three draw cards, etc.) get sort of upset and say that maybe your strategy isn't working and possibly shift into something more similar to her strategy (like buying a Thief).
7. If attack cards are ignorable, ignore them.
8. Say 'good game' in an honest tone and imply that you are happy to be playing with her.
9. If you want to open Silver/Silver or maybe Woodcutter/Silver and she is going first, do what she does so that she'll feel confident and better about her strategy.
10. Play games that she is better at than you besides Dominion. Ticket to Ride is a great one that you mentioned.
That's all I have, I hope that your Dominion experience will get better based off of these!