My gf a feeder ?

So ive been dating my gf for about 6 months and with a lot of stuff shes done and said while we’ve been going out ik for a fact she likes chubby guys and likes me chubby and doesnt want me to get skinny but i cant tell if she just likes me chubby and just doesnt want me to lose weight or also wants me to gain it so i need advise on what i can do to subtly find out if she is a feeder or not or like anything i can jokingly say to find out so i need advise also if you wanna know any of the stuff that’s previously happened