Astevo,
Good thing about windsurfing is you can just throw your stuff in the car and go out. I guess sailing requires a bit more to arrange.
I'm probably only 9 months ahead of you, comfortable in harness, but only a few sessions in footstraps.
started on bic techno 293od, now using 140 litre JP. If you're a bit wobbbly on a 150 I'd have thought a 120 might be too small. Having said that I feel I could downsize the 140 after only 6 months of use but will probably get another year out of it. So maybe 130??
I dont think you will use the 5.0 sail much at the moment, maybe a 5.5, 6.5, 7.5 would be better range...although it is good to have a smaller sail for those crazy wind days (rare at the moment)
I went with NP 5, 5.7, 6.7...and this weekend just got a 8 naish... Tried it out today and surprised how it didnt really feel all that big /scary and i think I could get planing on this in maybe only 10 knts (sadly, wasnt even that today). I can tell it will be very interesting in 15+ knts! This has opened up those marginal days now..so that's why I say 7.5 might be good for you to have.
I think you'll be amazed at the progress you make in the first year if you throw yourself into it and go out whenever you can. I used to see people flying past me at crazy speeds, thinking I'd never be able to go that fast....but now I can and it is AWESOME.
So don't worry about the lack of wind at the moment, when it comes, it more than makes up for it.
Andy
PS - if you want somebody closer to your own level to sail with, just shout. Most people out at botany are years ahead...decades even , lol