Knee problem since 10yrs old now 35yrs,

Hi, I'm a 35yr old female. I have a knee problem since first surg at age 10( FIST size Bakers cyst with no other problems). I was through a meniscus repair at age 16,another tear or 2 at age 19 along with another bakers cyst(arthroscopic then open surg to remove cyst back of knee, again removal and repair of tears when i was 32yrs old. Now 35 and have ; grade ll Interameniscal signal involving both menisci with suspicion for tears involving both menisci as well as additional injury involving the free surface of the posterior horn of the medial meniscus ; small joint effusion,along with a small popliteal cyst. kinda the summery of it all. i am in pyhsical therapy now oh did i mention also i have 2 bulding disc L4&5. im a lil scared of why this is happening to me and is surgery worth it again? My granmom had the same as I.I also had a total body bone scan, which all is neg =0)... am I a prime candidate for rhemumatoid arthritis and knee replacement. thank you in advance, Kim (tired in NJ)