How to not gain fat?

re full body v split routine

I have made far, far, more progress on a full body routine (stronglifts 5x5) than I ever did on split routines. I made the classic mistake of thinking that because I'd spent a few months moving dumbbells up and down, that made me an "intermediate" lifter and that I should be doing split routines. Fact was during the whole time I was doing that, I wasn't using heavy enough weights and wasn't progressively adding weight. Then on my split routine although I was using heavier weights (e.g. using a barbell for the first time) I wasn't making much progress, the isolation exercises I made no progress at all, the compound exercises progress was slow. After I switched to stronglifts the amount of weight I could lift went up very quickly in a short time, and also my muscles got bigger, and the ones i was trying to make bigger doing isolation exercises before, actually started getting bigger when i started doing stronglifts (i.e. with no isolation work at all).

So I totally second the advice to do a full body routine that's based on compound lifts with progressive increase in weight like stronglifts (there's a few similar programs out there, any of the good ones will do) until you get to the point that you're no longer making much progress with those, at which point you'll be an intermediate lifter and need an intermediate program, and that would include some kind of split routine.

Not sure what you mean by "don't want it to be a waste of money" - stronglifts 5x5 is a free download, Starting Strength by Mark Rippetoe (a similar program) Is a book and not very expensive (about 10 dollars on amazon).......... if you paid someone to design you the split routine you could always go back to that later on.

I'm eating at a surplus to make strength/weight gains, and to answer your original question, I feel like I've gained fat but the calipers say I've gained very little if any, some inch measurements have gone up, others have gone down, most of the ones that have gone up it's where the muscles have got bigger. I still fit in the same clothes, although my skinny jeans which used to fit my perfectly are now too tight in the quads/lower thigh and too loose in the lower butt area, because my quads got bigger and my butt got "perkier" (i.e. moved upwards). Bizarrely, I lost an inch from my hips even though I was bulking and gaining weight.

I'm not tracking my food intake, I'm just paying attention to nutrition, i.e. ensuring i eat plenty of protein, healthy fat, carbs, vitamins, minerals and fibre. I never let myself go hungry. I'm working on the principle that if I stimulate my muscles enough to grow my body's going to increase my appetite to make that happen... this was kind of an experiment, i.e. if i gain weight doing this I carry on like that, if I don't then I go back to tracking. So far I've gained 5-7lb doing this. If the weight gains stall then I'll start tracking.