Geometrical Isomerism (Cis-Trans) in trans-2-fluoro-3-methylpent-2-ene
The structure you drew



is ‒ according to the CIP-rules ‒ (E)-configured.  These rules are applied on each side of the double bond; namely


C of the ethyl group has a higher priority than C of the methyl group
F has a higher priority than C
C(ethyl group) opposes F, as seen across the double bond


This is not in contradiction that the two methyl groups are opposing each other, are in (trans)-relationship with each other.

In instances with only two subsitutents around a double bond, like (E)-2-pentene, you may use (E), derived from German "entgegen", literally "opposing", as synonym to (cis).  For the opposite instance, (Z), derived from German "zusammen", like "together", to describe a (trans)-configuration.

In instances with three or four substitutions around a double bond, and instances of several conjugated double bonds, follow IUPAC and adhere to the (E/Z) notation; which is absolute and not ‒ as (cis/trans) ‒ relative and potentially ambiguous.  See the example E/Z notation, for example. (Or, as one teacher told me, "stay on the E-Z pass".)