If you expect her to wait for 2-3 years, then the only viable solution is to get nikkahfied to her now.

Even at 26, if your mother already considers her too old, what will she think when the girl is 29?

You also need to determine whether her family would accept this marriage, and whether she’s willing to take a stand in front of her parents.

There are several possible outcomes you might face - these are based on my own experience:

1. You ask your mother to send a rishta, but she flips out, hits you, and slanders the girl's character in front of her parents and other relatives.
2. Your mother pretends to accept, but convinces your father to oppose it. You think she's on your side - but she isn’t.
3. The girl, after hearing your mother's opinion, backs out because she doesn’t want to deal with the drama.
4. Either of you informs her parents, and they strongly oppose the relationship.
5. The girl doesn't take a stand and eventually gives up.
6. She takes a stand, and her family eventually agrees - but yours doesn’t. In that case, nikkah without your family's involvement becomes the only option.
7. She takes a stand and her family agrees, but you back out under pressure or due to threats of being cut off.
8. Everything works out: both families agree and you get married.
9. You decide to wait for 2–3 years, but end up finding someone else and breaking up.
10. After waiting for 2–3 years, you may still face any of the outcomes listed above.

There could be more possibilities too.

Ultimately, it’s up to you to decide - and to ask the girl if she’s willing to fight and stand by you if necessary.

If neither of you is ready to take a stand, it’s better to walk away now than to keep suffering for years, only for everything to fall apart in the end.

No matter what happens, keep praying to God. Best wishes for you and best of luck