Do you know how many shares are outstanding, i.e., what % of the company you'd be getting?
Moreover, you should absolutely ask for the preferred price at the last fundraise. They should be able to give you that figure, just like they gave you the strike price.
Also ask about liquidation preferences: do investors get paid out at a multiple?
Finally, you should adjust that figure depending on how long ago the raise was. A 2021 valuation is very very different from a 2022 and 2023 valuation.
Once you have all of these figures, you can build yourself a probability-weighted model that factors in dilution and a few different outcomes (company ends up being worth nothing, company gets sold to PE at some small multiple, company has an IPO etc) come up with an expected value for the worth of your equity.
If you'd like, email me, and I'll share a redacted version of the model I give my employees at interviewing.io to do some reasoning about the value of their equity: aline@interviewing.io
P.S. Odds are that this equity is going to be monopoly money (because that's true for every company)... and odds are your stake is very small even if it's not because you're coming in late.