I seem to have a problem with playing up strokes, i don't know why. Just playing up and down strokes i seem to struggle.

Anyone point me in the right direction here?
Holding the pick wrong? Wrong angle? No sense of rhythem? I don't know, lol.

Help appreciated and thanks in advance.
just think of the off beats.

subdivide the beats in your head and play on the off beats

for example

if youre counting

1 2 3 4


1 & 2 & 3 & 4 &

and play on the &s

and start slow i guess.
Is it the actual upstrum motion that you have trouble with? If so, try playing guitar with nothing but upstrums. Work on speed. Once you can play songs quickly using upstrums, work on down/up motions. Sooner or later, you'll get better at it.