I read your inquiry and the replies with considerable interest. Your pictures do not seem altogether bad, but beauty is in the eye of the beholder and you may have expectations of more contrast than the next person. If you want to see more contrast, you will need to expose and develop the film to maximize the contrast range. This will occur at, or near, the rated speed of the film. Film speed ratings are intentionally skewed toward the faster end so you have more latitude in shooting it at a slower speed than at a faster speed. A typical film may produce the optimum contrast at 1/2 stop above the rated speed, but may also produce equal contrast at 1 1/2 to 2 stops slower speed. Companies want to convince people their film is fast so they use ratings that are very near the upper end of the optimum exposure range. Taking your 125 rated film and using it at 150 or higher is almost guaranteed to result in loss of contrast in the negatives. Some of this can be corrected by push processing but there is never a free ride and you will increase the grain of the negative.
Here are some suggestions. First, get yourself a gray card. In a pinch, you might find a "dove gray" matte board or even paper at an art supply store. This is to produce the 18% reflectance that your camera's meter is designed to work with. No matter what meter arrangement you use, your camera is attempting to AVERAGE the light in the scene you are photographing. The contrast you are looking for is not based on the average light but on the darkest and brightest parts of the scene. If you want to conduct a test of this, try taking a picture of a gray card against a dark background, and then another one against a light background. The card will come out two completely different shades because the background throws the light meter off.
Now, place the gray card so it is at the same angle as the primary subject of your picture.
Take a light meter reading from the card and the meter will figure the proper exposure based upon the sun angle and the light available. Use this exposure for your pictures.
If you use a fill flash, do not change the exposure. Changing the exposure will underexpose the rest of the image because the flash will only illuminate objects within about 12 feet of the camera. If your flash washes out the subject, then your flash is too bright or too close to your subject.
All that stuff about commercial photo printers is pretty much true. Some do use color paper. Some even print digitally, on printer paper, not photo paper at all. Their ability to properly process B&W is often limited. However, I have found places that did an excellent job and use good, quality B&W paper. If you mail it to them, you may have no way of knowing what they do. If they are local, ask them for a tour.
I hope this information is useful,